Added a stack specific config file for trusty.  This replaces the hard coded config which was added in [this commit](https://github.com/cloudfoundry/php-buildpack/commit/4f32fe096ec92ee2126e2f4b7081b7e0e7fc8a11).
Added a stack specific config file for trusty.  This replaces the hard coded config which was added in [this commit](https://github.com/cloudfoundry/php-buildpack/commit/4f32fe096ec92ee2126e2f4b7081b7e0e7fc8a11).

lloydbadger/test,svrc-pivotal/php-buildpack,hjooyang/php-buildpack-3.2.2-,apawar2/php-buildpack,hpcloud/php-buildpack,nsharma283/php-new,svrc-pivotal/php-buildpack,ashish17das/cf-php-build,zhangyanfa/yanfaz-php-buildpack,arjankroontolsma/post2,skeeso/php-buildpack,hpcloud/php-buildpack,zhangyanfa/yanfaz-php-buildpack,hjooyang/php-buildpack-3.2.2-,tgemal00/php-buildpack,UNINETT/php-buildpack,chregu/cf-php-varnish-buildpack,hairmare/php-buildpack,hairmare/php-buildpack,lloydbadger/test,jsloyer/php-buildpack,cf-identity/php-buildpack,jan-randis/php-db2-mysql-buildpack,LeonidLe/php-buildpack,zizhongwei/php-buildpack-master,cloudfoundry/php-buildpack,nsharma283/php-buildpack,cloudfoundry/php-buildpack,zizhongwei/php-buildpack-master,jsloyer/php-buildpack,hjooyang/php-buildpack-3.2.2-,nkatre/php-buildpack,hairmare/php-buildpack,zizhongwei/php-buildpack-master,nsharma283/php-new,nsharma283/php-buildpack,cloudfoundry/php-buildpack,arjankroontolsma/post2,LeonidLe/php-buildpack,svennam92/php-buildpack,hjooyang/php-buildpack,aronreid/cf-php-buildpack,cf-identity/php-buildpack,skeeso/php-buildpack,apawar2/php-buildpack,apawar2/php-buildpack,svrc-pivotal/php-buildpack,ArthurHlt/php-buildpack,UNINETT/php-buildpack,jan-randis/php-db2-mysql-buildpack,lloydbadger/test,Orange-OpenSource/cf-php-build-pack,aronreid/cf-php-buildpack,aronreid/cf-php-buildpack,svrc-pivotal/php-buildpack,mc500/php-buildpack,arjankroontolsma/post2,mc500/php-buildpack,jsloyer/php-buildpack,Orange-OpenSource/cf-php-build-pack,zhangyanfa/yanfaz-php-buildpack,cf-identity/php-buildpack,chregu/cf-php-varnish-buildpack,aronreid/cf-php-buildpack,svennam92/php-buildpack,nsharma283/PCF-php-buildpack,zhangyanfa/yanfaz-php-buildpack,svrc-pivotal/php-buildpack,nkatre/php-buildpack,zizhongwei/php-buildpack-master,hjooyang/php-buildpack,apawar2/php-buildpack,ashish17das/cf-php-build,aronreid/cf-php-buildpack,hjooyang/php-buildpack-3.2.2-,LeonidLe/php-buildpack,nsharma283/PCF-php-buildpack,svrc-pivotal/php-buildpack,zizhongwei/php-buildpack-master,mc500/php-buildpack,tgemal00/php-buildpack,chregu/cf-php-varnish-buildpack,cloudfoundry/php-buildpack,mc500/php-buildpack,nkatre/php-buildpack,ochamber/cf-php-build-pack,cf-identity/php-buildpack,nsharma283/PCF-php-buildpack,jsloyer/php-buildpack,hjooyang/php-buildpack,nsharma283/PCF-php-buildpack,tgemal00/php-buildpack,cloudfoundry/php-buildpack,nsharma283/php-new,svennam92/php-buildpack,LeonidLe/php-buildpack,lloydbadger/test,cloudfoundry/php-buildpack,UNINETT/php-buildpack,nsharma283/php-new,tgemal00/php-buildpack,ashish17das/cf-php-build,nkatre/php-buildpack,skeeso/php-buildpack,jsloyer/php-buildpack,thesrinivas/php-buildpack,cloudfoundry/php-buildpack,lloydbadger/test,nkatre/php-buildpack,hpcloud/php-buildpack,hjooyang/php-buildpack,ochamber/cf-php-build-pack,jsloyer/php-buildpack,skeeso/php-buildpack,arjankroontolsma/post2,jan-randis/php-db2-mysql-buildpack,ochamber/cf-php-build-pack,nsharma283/php-buildpack,thesrinivas/php-buildpack,ochamber/cf-php-build-pack,zizhongwei/php-buildpack-master,hjooyang/php-buildpack-3.2.2-,ArthurHlt/php-buildpack,mc500/php-buildpack,jan-randis/php-db2-mysql-buildpack,hjooyang/php-buildpack,tgemal00/php-buildpack,hpcloud/php-buildpack,chregu/cf-php-varnish-buildpack,cf-identity/php-buildpack,Orange-OpenSource/cf-php-build-pack,lloydbadger/test,ashish17das/cf-php-build,UNINETT/php-buildpack,nsharma283/PCF-php-buildpack,ashish17das/cf-php-build,nsharma283/php-buildpack,thesrinivas/php-buildpack,apawar2/php-buildpack,ochamber/cf-php-build-pack,hairmare/php-buildpack,ArthurHlt/php-buildpack,svennam92/php-buildpack,UNINETT/php-buildpack,cf-identity/php-buildpack,skeeso/php-buildpack,svennam92/php-buildpack,zhangyanfa/yanfaz-php-buildpack,thesrinivas/php-buildpack,thesrinivas/php-buildpack,jan-randis/php-db2-mysql-buildpack,UNINETT/php-buildpack,hairmare/php-buildpack,nsharma283/php-buildpack,mc500/php-buildpack,ArthurHlt/php-buildpack,hpcloud/php-buildpack,svennam92/php-buildpack,hairmare/php-buildpack,apawar2/php-buildpack,hjooyang/php-buildpack,hjooyang/php-buildpack-3.2.2-,zhangyanfa/yanfaz-php-buildpack,ArthurHlt/php-buildpack,chregu/cf-php-varnish-buildpack,LeonidLe/php-buildpack,nsharma283/php-new,hairmare/php-buildpack,ashish17das/cf-php-build,nkatre/php-buildpack,nsharma283/php-new,tgemal00/php-buildpack,nsharma283/php-buildpack,hpcloud/php-buildpack,ArthurHlt/php-buildpack,ochamber/cf-php-build-pack,LeonidLe/php-buildpack,thesrinivas/php-buildpack,arjankroontolsma/post2,cf-identity/php-buildpack,aronreid/cf-php-buildpack,chregu/cf-php-varnish-buildpack,nsharma283/PCF-php-buildpack,skeeso/php-buildpack,arjankroontolsma/post2,jan-randis/php-db2-mysql-buildpack