Fix reference to 'long'

For all instances of `(int, long)`, change to six.integer_types. For
all other references to `long`, change to `int` through lib2to3.

For #20
Merge remote-tracking branch 'upstream/master' into fix_long_call
Merge remote-tracking branch 'upstream/master' into fix_long_call
Merge pull request #79 from brettcannon/fix_long_call

Fix references to 'long'