Major health check refactoring.

- Modified protocol buffer backing health checks
- Task health checks are now executed by short-lived, per-request actors
- Upgrades akka and spray library versions
Merge branch 'master' into wip-health-checks-refactored
Fix #200 Add version to tasks
Merge pull request #207 from BenWhitehead/bug-200

Fix #200 Add version to tasks
Added jackson-case-class-module to the build.
jackson-case-class-module integration

Bumped jackson-case-class-module dependency to 0.1.0

Primitive JSON API types are now modeled using Java boxed types, which allows for the expected default values to be set when missing from the source JSON during deserialization.
Regenerated REST documentation
Removes mistakenly committed comment
Removed @Provides method for HealthCheckManager
Merge pull request #215 from mesosphere/case-class-module-test

Case class module for Jackson
Add "id" search for feature parity with V1 API

The V1 API "search" endpoint allows searching both on "cmd" and on "id".
V2 already supports "cmd", and so this adds "id" to make V2 on par with
V1's functionality.

Example:

    curl -H "Accept: application/json" localhost:8080/v2/apps?id=hadoop_
Refactor `search` to be more readable per feedback
Merge pull request #216 from mesosphere/v1-v2-search-parity

Add "id" search for feature parity with V1 API
Return apps matching the filter, not those that don't

This was returning the set of apps that did not match the filters. It
should return apps that match one or more of the filters.
Add healthCheckResults to the apps task resource
Merge pull request #217 from mattstep/wip-health-checks-refactored

Add healthCheckResults to the apps task resource
Rebase: master
Update README.md
Add 'Apache'; Make opening README paragraph more natural
Send full app state in PUT example

PUT expects the full state of a resource. Sending only the "instances"
attribute is misleading since the functionality is not guaranteed to
work like PATCH requests.