packages cache by caching wp http api
packages cache behat tests
stricter update package from cache test
better validation of urls as cache key
include symfony finder in phar

… and remove duplicate dependency in composer.json from a rebase
make WP_CLI::get_cache more readable and private
fix undefined index notice
fix composer.json whitespace
Merge branch 'master' into packages-cache
fix missing EOF newline
Merge pull request #619 from francescolaffi/packages-cache

cache package downloads