Deleting client and demo app from main Mistral repo

Change-Id: Ib4e1deb0bcad53b55478b00f7f8a203186af305f
Fixing and refactoring authentication

* Moved pecan configuration to oslo config
* Refactored functional base test
* Got rig of thread local related code in mistral/context.py
* Added new exception ApplicationContextNotFoundException
* Fixed example configuration file
* Made minor cosmetic changes (blank lines, naming)

Change-Id: I1899ce2562a34ebafa20c5735bdf4f0c80dd0175
Merge "Deleting client and demo app from main Mistral repo"
Merge "Fixing and refactoring authentication"