Correct handling of fontforge execution

[rogercampos]

Fontcustom shouldn't be checking if the fontforge output is 5 lines length to detect an error, instead it should check for the exist status, code here:

https://github.com/FontCustom/fontcustom/blob/master/lib/fontcustom/generator/font.rb#L82

In my case fontforge is giving a warning deprecation message:

Copyright (c) 2000-2009 by George Williams.
 Executable based on sources from 23:48 GMT 23-Sep-2009.
 Library based on sources from 17:32 GMT 14-Sep-2009.
../../shared/bundle/ruby/1.9.1/gems/fontcustom-1.0.0/lib/fontcustom/scripts/generate.py:3: DeprecationWarning: the md5 module is deprecated; use hashlib instead
  import md5
{"glyphs": ["shipping", "transfer", "packaging", "recurring-user"], "fonts": ["backoffice.ttf", "backoffice.woff", "backoffice.eot", "backoffice.svg"], "file_name": "backoffice"}

That is wrongly interpreted as an error.

[kaizau]

Good catch. Closed by #99.