Fixed #256. Update plugin discovery.
Merge pull request #257 from yeukhon/new-auto-discovery

Fixed #256. Reorganize plugin structure: plugin class now lives in init....
Fixes #261 Create a Vagrant configuration for backend development
Fixes #266 Generate an API Key when creating new users
Fixes #267 Add API to retrieve list of scans for a specific site and plan
Fixes #268 ZAP Plan uses wrong plugin name
Merge branch 'master' of https://github.com/st3fan/minion-backend
Fixes #270 Allow third party apps to receive a callback when a scan changes state
Fixes #217 Basic plugins should return a unique code for each issue
Fixes #272 Add a limit and default sort order to /scans
Fixes #273 Allow /sites API to filter on URL
Fixes #274 Allow GET /plans to take a name argument
Fixes #275 Add API to search for issues