Change Travis build environment to trusty
Change Travis build environment to trusty

precise does not have libgpgme11>=1.3 and trusty does, so change this
so we can get gpgme availability on travis.

Signed-off-by: Mark Weiman <5ec563e4a04e792e739af320cc9c0c01664c7306@markzz.com>

markzz/php-alpm,markzz/php-alpm,markzz/php-alpm