Force using latest dev version of "phpspec/phpspec" & "phpspec/prophecy"

Additionally it fixes broken spec in last commits.

Note this is required till there will be stable release of `phpspec/prophecy`, otherwise some specs will fail because of issue with non-existing classes while specing.

Additionally change in `omnipay/omnipay` lock data will be always forced to this as Packagist containts old references (it's not auto-updated like Github symlinks), so __please__ don't comment about it.