Use entry_points instead of scripts in setup.py

This allows a fine-grained control of the dependencies, because it generates a wrapper script
that calls the specifiend function (i.e., main inside cheat/app.py)

bin/cheat

@@ -1,61 +0,0 @@
-#!/usr/bin/env python
-
-"""cheat
-
-Usage:
-  cheat <cheatsheet>
-  cheat -e <cheatsheet>
-  cheat -s <keyword>
-  cheat -l
-  cheat -d
-  cheat -v
-
-cheat allows you to create and view interactive cheatsheets on the
-command-line. It was designed to help remind *nix system
-administrators of options for commands that they use frequently,
-but not frequently enough to remember.
-
-Examples:
-  To look up 'tar':
-  cheat tar
-
-  To create or edit the cheatsheet for 'foo':
-  cheat -e foo
-
-Options:
-  -d --directories  List directories on CHEATPATH
-  -e --edit         Edit cheatsheet
-  -l --list         List cheatsheets
-  -s --search       Search cheatsheets for <keyword>
-  -v --version      Print the version number
-"""
-
-# require the dependencies
-from cheat import *
-from cheat.utils import *
-from docopt import docopt
-
-
-if __name__ == '__main__':
-    # parse the command-line options
-    options = docopt(__doc__, version='cheat 2.1.3')
-
-    # list directories
-    if options['--directories']:
-        print("\n".join(sheets.paths()))
-
-    # list cheatsheets
-    elif options['--list']:
-        print(sheets.list())
-
-    # create/edit cheatsheet
-    elif options['--edit']:
-        sheet.create_or_edit(options['<cheatsheet>'])
-
-    # search among the cheatsheets
-    elif options['--search']:
-        print(colorize(sheets.search(options['<keyword>'])))
-
-    # print the cheatsheet
-    else:
-        print(colorize(sheet.read(options['<cheatsheet>'])))