Add configuration parameters to maven plugin for specifying directories and main.js template

[victorzinho]

Add two configuration parameters on jwebclient-analyzer-maven-plugin to specify directories for both web resources and plugin descriptors (which can reside in different directories).

Also add a configuration parameter to specify the main.js template to use.

Default values for directories are 'nfms' and default main.js template is the one included with the plugin.