Fix some generics warnings, add javadoc
XD-847 Revise the available hadoopDistro options

Available options now are hadoop12 (default), cdh4, hdp13, phd1, hadoop20
XD-880 Update Java Version to 7
Applied copy logic to the mail source module

Note that the mail modules does NOT work in this setup. Purpose of this
commit is to review build logic.
Apply new build to all mail related modules
Slightly better eclipse experience
Use flattened project names.

Prevent detection of intermediate folders as projects.
Prevent project collision of the same name (e.g. mail as both
source and sink)