Add unit-tests to signup

[medhach]

Unit tests will help improve the application performance.

[muddlebee]

@medhach Im starting off with this first ? If you don't mind :)

[muddlebee]

@medhach one doubt. the unit tests shall cover. tests for (https://github.com/systers/macc/blob/develop/signup/views.py) all the functions. and urls.py too ?
Are you active on slack ? If I need to discuss something it would be smooth over there. :)

[medhach]

@anweshknayak Sure, you can start with this. The tests for all the functions should suffice. :)