Merge pull request #169 from johanatan/master

Fix for #167. Return '201 - Created' from POST /v2/apps rather than '204...
Change version to 0.5.0-SNAPSHOT
reorg README and link to latest release
Use Travis CI to build/upload runnable jars to s3
Misc travis-ci build tweaks

* Add faraday_middleware gem to address travis-artifacts error:
    /home/travis/.rvm/gems/ruby-1.9.3-p484/gems/faraday-0.9.0.rc7/lib/faraday.rb:189:in `lookup_middleware': :json is not registered on Faraday::Response (Faraday::Error)
* Move gem install to after_success so builds that fail, fail faster
* Make PROJECT_VERSION available to all build stages
Pin to faraday version 0.8.9

To address: https://github.com/travis-ci/travis-artifacts/issues/23
Farady 0.8.9 is the latest version known to work with travis-artifacts.
Add shasum and adjust upload paths
TRAVIS_BRANCH may have spaces

(Also test that artifact uploads with the same version will overwrite
each other.)
Updates per Toby's review.
Merge pull request #173 from johanatan/feature/tasksKillReturnErrorCode

Fix for #107. Return 404 if tasks to kill cannot be found.
Make sure 404 responses have the proper mime type and a message. Fixes #176
Add companies using Marathon
Fixed #170 - App update ignores value for URIs.
Merge pull request #178 from mesosphere/cleanup_404

Set proper mime type and message on 404 responses. Fixes #176
Build a tgz artifact modeled on past releases
Use a hyphen instead of underscore
Use a hyphen instead of underscore
Merge pull request #177 from mesosphere/artifact_publishing

Automatically upload marathon build artifact (tgz) to s3 with shasum
Fix for #109. Prevents negative integers being specified for number of instances.
Merge branch 'preventNegativeInstances'