Do not download entire PF history
Do not download entire PF history

Limit git history to 50 commits when building.
This number is completely arbitrary, it is the one travis uses.

Signed-off-by: Kevin Rocard <f6672397850e914591889d29dcaf9077eb1a8a4f@intel.com>

krocard/parameter-framework,krocard/parameter-framework,clero/parameter-framework,01org/parameter-framework,mgaio/parameter-framework,krocard/parameter-framework,mgaio/parameter-framework,miguelgaio/parameter-framework,miguelgaio/parameter-framework,dawagner/parameter-framework,01org/parameter-framework,dawagner/parameter-framework,miguelgaio/parameter-framework,clero/parameter-framework,dawagner/parameter-framework,mgaio/parameter-framework,clero/parameter-framework,01org/parameter-framework