Add a post deploy hook to install Procfile

- Virtual environment will be linked in to the current directory in
  'venv'
- Procfile now gets created by the post deploy hook which is called by
  capistrano
Remove log directory

This is handled by capistrano at deployment now. The log directory is
created in shared and symlinked into release.
Health check URL for backdrop read API

@pbadenski
Merge pull request #33 from alphagov/capistrano-deployment

Add a post deploy hook to install Procfile
Merge pull request #38 from alphagov/backdrop-read-healthcheck

Health check URL for backdrop read API
Extract mongo integration code from repository

@gtrogers
@maxfliri
Fix typo on post deploy hook

env does not live in /usr/local
Merge pull request #40 from alphagov/post-deploy-typo

Fix typo on post deploy hook
Refactor logging and change log file name

- Move duplicate setup into log_handler module
- Use [environment].log for both read and write
  When deployed read and write are their own applications so there is no
  overlap.
Change order of arguments to find

@robyoung
@maxfliri
Tests for mongo driver

@maxfliri
Inject mongo into repository

@robyoung
@maxfliri
Migrate part of repository test to unit tests

@robyoung
@maxfliri
Merge pull request #42 from alphagov/refactor-mongo-layer

Extract mongo integration code from repository
Merge pull request #41 from alphagov/logging-refactor

Refactor logging and change log file name
Add newline

Fix my OCD.
Add log directory

Tests failed otherwise, since the directory doesn't exist where
it tries to create the log files.
Constrain healthcheck HTTP methods
Add test for _status allowed methods
Merge branch 'master' into refactored_feature_tests

Feature tests have moved into sub directories to better organise them.