Update default php versions. [#156256902]
Update default php versions.
[#156256902]

Signed-off-by: Leah Hanson <59915d4d5a651c1df4fd522b917423b47c84f68b@pivotal.io>

cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack,cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,cloudfoundry/php-buildpack,cf-identity/php-buildpack