Fixed an issue with render_to_string

render_to_string requires a dictionary for arguments. Without this fix it caused an error.
Merge branch 'release/0.2.1' into develop
Markitup library updated
Create jQuery global variable (django 1.6 compatibility update)
Added markdonw and markdown_safe template filters
Don't call removeMarkItUp in init (it wipes out textarea when markitup is not active)
jquery.markitup.js updated again (not it's safe to call remove() twice)
Fixed 'preview' button.

1. CSRF protection made by examples in django docs (previous version was broken)
2. Use 'markdown' template tag from django_markdown (django.contrib.markup was deleted from django 1.6)
3. Use new django.shortcuts.render signature in views.py.
Merge pull request #9 from harabchuk/patch-1

Fixed an issue with render_to_string
Add basic tests
Merge Alexey's commits
Connect travis
Update README
Update version
Merge branch 'release/0.2.2'