travis: exclude 'install' directory from coverage PATH
travis: exclude 'install' directory from coverage PATH

The directory used to install the PF was covered. Thus,
include files were covered twice.
This patch removes this directory from the coverage PATH.

Signed-off-by: Jules Clero <2deac8eb6d4468174a95d7398a201f3232180ec0@intel.com>

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