Added project-info flag to depmap goal

Review Request #600 — Created June 26, 2014 and submitted — Latest diff uploaded

ity, johanoskarsson, jsirois
Prints source roots, dependencies, and paths to libraries for targets and their dependencies in json format. 
It can be run with: ./pants goal depmap /path/to/target --depmap-project-info

Adding the -format flag causes the output to return a single line of json:
./pants goal depmap /path/to/target --depmap-project-info --depmap-format

This functionality will be used for project import in the IntelliJ Pants plugin.
Added tests for the goal (, they pass runs successfully