Allow user to specify IntelliJ module name that is generated

In reference to this mail thread - http://www.nabble.com/Specifying-IntelliJ-module-name-with-maven-idea-plugin-tf3756364s177.html

Currently IntelliJ module name that is generated is derived solely from artifactId.

IntelliJ module name has to be unique within a project and this can cause conflict when maven project structure has several sub modules of the same name. i.e.,

project/
+- common/webapp/
+- customer/webapp/

I'm proposing that
a) the default module name should be derived from pom's project name (rather than artifactId). (as I understand it the project name is merely used for console log display and it would make sense for user to make it unique within his/her project structure).
b) that the plugin should provide a configuration parameter to override this default behaviour.

Currently I have hacked the plugin to use $

.$

as the generated IntelliJ module name. I can do abit more work to provide a patch if needed.