Support creating Image from SplFileInfo object
Use Mockery at 0.9.x@dev

An issue in Mockery (https://github.com/padraic/mockery/issues/348)
prevented SplFileInfo classes from being mocked.

This commit changes the Mockery version requirement to 0.9.x@dev, as it has been
fixed in master, but not yet tagged as a release.
Merge pull request #216 from jwpage/splfile_support

SplFileInfo support