Merge pull request #227 from andylyall/develop

Fix Typo in HealthChecks
WIP: Spot Instances rework
Checkstyle fixes
Spot VMs re-work cont: floats for prices are back for consistency with the rest of the API.
Merge pull request #228 from maksimov/develop

Spot VMs
Getters for time interval in filter
Adding timestamps to the matcher.
:bangbang: Added the spot vms capability, driver fixes to follow.
Adding missing getters and annotations
Merge pull request #231 from maksimov/develop

Adding SpotPrice timestamps filtering
Merge Fixes