Add missing call to super in JSONType.__init__

Fixes https://github.com/kvesteri/sqlalchemy-utils/issues/57.
Added URLType to global import
Merge pull request #58 from thusoy/master

Add missing call to super in JSONType.__init__
Fixed Typo for URLType
Merge pull request #59 from kelvinhammond/patch-1

Added URLType to global import
Refactor weekday
Merge branch 'master' of github.com:kvesteri/sqlalchemy-utils
Remove file type, will be implemented using separate table and silo package later
Remove NumberRange, say hello to intervals
Add int range canonicalization
Rename test case
Rename number range file
Remove futile import
Add range class
Add initial draft for RangeComparator
More tests for comparator
More tests for range coercion
Add new range types
Fix range properties
Fix DateTimeInterval ref