very basic start for custom, user-provided routes (Issue #48)

- changes to psiturk-setup-example
   - now create a folder for the files to live in
   - includes a default 'custom.py' showing how to add custom routes
   - files moved around so that they can be copied easier (all reside in psiturk/example now)
oops, lost these files due to .gitignore
moving authentication out as a importable module for end-users

- users providing custom routes might want to password protect them (e.g., those providing custom views of data, etc...)
- this provides a class-based decorator which can do this
boom!  this works (easier than expected).  here's a nicer example to show how

- example custom.py script showing how to access various customizable features
- who want to write /calculate_bonus (?)
hides the default custom.py from the psiturk import path  (Closes #48)

kind of hacky, but works for now
Merge remote-tracking branch 'origin/custom_routes' into dev

Conflicts:
	psiturk/version.py