Fix ImportError
[ujson] Fixing seg faults in unit tests

- The following unit tests were causing segfaults:
```
test_doubleLongDecimalIssue
test_invalidDoublePrecision
test_doublePrecisionTest
test_encodeDecimal
test_doubleLongIssue
test_encodeDecodeLongDecimal
```
- I changed a constant that couldn't be `const` because it can be overwritten by
  a passed in parameter
Merge pull request #131 from mvismonte/fix-seg-fault

[ujson] Fixing seg faults in unit tests
Merge pull request #116 from iskra/patch-1

Fix ImportError
[ujson] Added support for seralizing objects to JSON

- This is accomplished by calling the __unicode__ function on an object.
- Added unit tests to test this change.  It also seems that this should not be
  leaking memory according to the test in tests/tests.py