Initial test plan structure for Brahmaputra

Initial test plan structure for Brahmaputra

Created the initial structure for the plugfest test plan.
* Created a base directory and document structure
* Created contributor guidelines
* Created test case template
* adjusted for: http://artifacts.opnfv.org/releng/docs/how-to-use-docs/documentation-example.html
* cp: reformatted the directories and structure to use the RST format
  * (we cannot review odt format in our toolchain, so use rst)
* cp: added an index.rst structure to establish structure without numbering
* cp: will ad anothe job to include dovetail in the docs toolchain

Change-Id: I4ef997da51b3b85e391629d6e08fadf87257fc6a