Modified Bolt\Config to load theme configuration

Changed the parseConfigYaml method signature to allow for
fullpath loading to allow theme config files to remain within
the theme directory

Added code to load the theme config in the getConfigMethod
Add theme config as global twig variable

Theme configuration can be accessed in views using

	{{theme.foo}}
Merge pull request #856 from frostymarvelous/config-files-for-themes

Modified Bolt\Config to load theme configuration