Fix setting EC2 tags on slaves (broken in 1.17 by d5154c60).
Merge pull request #42 from meteor/set-tags

Fix setting EC2 tags on slaves (broken in 1.17 by d5154c60).
Add UI fields for Spot instances

Add in an optional block for enabling Spot slaves and specifying a max bid
price including help text.
Startup Scripts for Spot Instances

Spot instances can take a while to start up. These scripts are meant as
samples of how to set up an EC2 instance to register itself as a headless
slave to the Jenkins server when it has been launched.
Refactor EC2Slave to EC2SpotSlave and EC2OndemandSlave

Create an abstract super class for EC2 slaves with ondemand and spot
subclasses. If spot specific fields are provided, we spawn a EC2SpotSlave
which should be configured to register themselves with Jenkins. This prevents
Jenks from having to poll EC2 to check and see if the Spot instance has
started up prior to connecting to it via ssh. This also makes transitioning
to using persistant spot bids easier.
Add unit test for Spot configuration

Create unit tests that test the configuration of Spot slaves.
EC2 type is now displayed on node configure page. If the node is a Spot instance, the specified bid price will also be displayed.
Launcher page

Computer launcher now displays proper message for spot instances