Format dictionary for key string eval

ENH: Modified Dict() to clean up the keys generated from docopt, i.e. remove '-', '<', '>'.  Operations that evaluate the key strings will not throw a syntax error and **kwargs syntax is preserved.

Example:
----------------------------
"""
Usage:
  my_test --work
  
Options:
  --work   boolean
"""
import docopt

def my_function(work=False):
    if work:
        print "Do some work!"

if __name__ == "__main__":
    kwargs = docopt.docopt(__doc__)
    my_function(**kwargs)
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