save drone.yml on the build
add rebuild button for users who have admin access to the repo
always specify a branch when rebuilding
Update buildscript for old builds
Refactored Less StyleSheets

* started using less's shortucts
* removed vendor prefixes fron less file; use autoprefixer instead
* fixed spacing
* renamed all 0 values to 0
* converted all comments to silent comments
Fixed an Unhandled Error in badges.go

There was an unhandled error in badges.go. If you pass an invalid
branch to the badge handler (http://beta.drone.io/github.com/drone/drone/
status.svg?branch=this) the browser is told to redirect to a blank string.
This is unintended behavior. Now, a 404 response is sent instead.
serce => serve