Android : New errors after installation of fabric plugin in eclipse android

I use eclipse LUNA for android development. I installed Fabric plugin to add crashanalytics today and suddenly I am seeing some error which I am not able to identify.

The project shows red mark for errors but none of the files have the same error mark

And when I try to run/build the project I get the following error

An internal error occurred during: "Running GTM diagnose". com.android.tools.lint.detector.api.XmlContext: method (Lcom/android/tools/lint/client/api/LintDriver;Lcom/android/tools/lint/detector/api/Project;Lcom/android/tools/lint/detector/api/Project;Ljava/io/File;Lcom/android/resources/ResourceFolderType;)V not found

Also i am seeing this error repeatedly in the console

[2014-12-05 08:56:41 - com-crashlytics-sdk-android_answers] Unable to resolve target 'android-21' [2014-12-05 08:56:41 - com-crashlytics-sdk-android_crashlytics] Unable to resolve target 'android-21'

This is my first android project so sorry if this is a noob question. Any help would be appreciated