MathJax, registration support, flask-bcrypt & updated view permissions

[mjiao5151]

Dear friend:
I really like your work on this wiki app, reading your code have been a great learning experience.
I feel thrilled to contribute to this project.
the following are few modifications, hope it can fit your appetite.

1. add mathjax support, by using python-markdown-math extension.
2. add Registration form and corresponding template file
3. use bcrypt package to do the password encryption, save few lines of code.
4. modified view function permissions.

Hope that help!

[lordslair]

Hello everyone,

Just to drop a comment here, as I tried the original repo, and the PR proposed by @mjiao5151
I spawned his branch inside a container to check it, and as far as I can see, everything's working out-of-the-box without any problem.

I don't know if it will be merged into master, but it made me save a lot of time, as I needed that feature

Thanks to both of you

[alexanderjulo]

Hey @mjiao5151,

thanks a lot for these changes! I broke out mathjax in a separate PR (with the only change being that I checked in the JS, to make sure it will work offline also) and I will be merging it.

I also like the bcrypt change, however I believe it will not be backwards compatible. So I will technically have to issue a major release and add some release notes to make sure that people know what might have happened. I will do so some time next month.