add "internal_dir" option to sublime-settings

[newmen]

Sometimes when project is large and written at several languages, the ruby code could be placed in some internal directory. The spec directory where tests of ruby code is implemented also placed in it internal directory. For example see my project: versatile-diamond/analyzer
Current patch adds option to sublime-settings by which the internal directory could be set.

P.S. Using the before_callback and after_callback does not eliminate the problem.
For example:

  "before_callback": "cd analyzer",
  "after_callback": "cd ..",

does not work for me.