added tests for is_executable #21
meta updated
meta updates
Merge pull request #28 from thornag/1.1.x-is_executable

added tests for is_executable #21
Merge branch '1.1.x' of github.com:thornag/php-vfs into 1.1.x
added phpunit as dev dependency, removed coveralls
added symlink support (close #20)
fixed chmod when chmoding link