Remove "Automation core" dependency on "web common"

org.nuxeo.ecm.automation.TraceException: 

****** chain ******
Name: Auth.LoginAs
Exception: OperationException
Caught error: Failed to invoke operation Auth.LoginAs
Caused by: java.lang.NullPointerException
****** Hierarchy calls ******
	org.nuxeo.ecm.automation.core.operations.login.LoginAs

	at org.nuxeo.ecm.automation.core.impl.OperationServiceImpl.run(OperationServiceImpl.java:195)
	at org.nuxeo.ecm.automation.core.impl.OperationServiceImpl.run(OperationServiceImpl.java:116)
	at org.nuxeo.ecm.automation.server.test.CanLoginAsTest.loginAsSystem(CanLoginAsTest.java:32)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$InvokeMethod.evaluate(FeaturesRunner.java:354)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
	at org.nuxeo.runtime.test.runner.FeaturesRunner.run(FeaturesRunner.java:298)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: org.nuxeo.ecm.automation.OperationException: Failed to invoke operation Auth.LoginAs
	at org.nuxeo.ecm.automation.core.impl.InvokableMethod.invoke(InvokableMethod.java:157)
	at org.nuxeo.ecm.automation.core.impl.CompiledChainImpl.doInvoke(CompiledChainImpl.java:124)
	at org.nuxeo.ecm.automation.core.impl.CompiledChainImpl.invoke(CompiledChainImpl.java:110)
	at org.nuxeo.ecm.automation.core.impl.OperationServiceImpl.run(OperationServiceImpl.java:169)
	... 25 more
Caused by: java.lang.NullPointerException
	at org.nuxeo.runtime.api.Framework.loginAsUser(Framework.java:290)
	at org.nuxeo.ecm.automation.core.operations.login.LoginAs.run(LoginAs.java:52)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.nuxeo.ecm.automation.core.impl.InvokableMethod.doInvoke(InvokableMethod.java:135)
	at org.nuxeo.ecm.automation.core.impl.InvokableMethod.invoke(InvokableMethod.java:149)
	... 28 more