A few enhancements

Major changes are:
* All the dependencies defined in both compile & runtime configurations are added to Coverity class path. This will allow the dependencies defined in custom configurations like “provided" to be available for Coverity to analyze.
* Improved usage documentation.
* Optionally the plugin can include all the sub-projects in Coverity analysis. This way the user doesn’t have to  apply the coverity plugin in all the sub-projects manually.
* Coverity server details & credentials can be specified via command line in addition to the previous approach of configuring them via XML file. Thus, these values can be easily configured in TeamCity.
* The Coverity installation location can be specified, if the coverity commands aren’t available in the PATH.