Fix #575: Add sphinx dependency to dev-requirements.
- Added Sphinx to the dev_requirements.txt file.
- Changed Sphinx version to 1.2.3 to reflect latest version.
- Removed docs/requirements.txt from docs and travis.yml.
Fix #584 unicode string format error, 'string' to u'string'
Fix #583 Chinese Translation problem

Fixes #583.
Presently, the translation rates for Traditional Chinese and Simplified Chinese are 100%