Merge pull request #137 from oscarfmdc/MYRIAD-309

MYRIAD-309 Update CHANGELOG for v0.4.0 release

MYRIAD-289 (re-open) Fix prepare_rc.sh with new GIT_URL (#123)

Fixed to: https://gitbox.apache.org/repos/asf/incubator-myriad.git

Update cgroups documentation - was missing a necessary yarn-site conf…

…iguration.

Fix minor typo hierachy->hierarchy.
Pull Request:
  Closes #65
Author: Darin Johnson <[email protected]>

Incorporated feedback from IPMC on RC2

- Added build instructions to generate a "gradlew" script when building Myriad from source downloads. Myriad's source releases will henceforth exclude the "gradlew" script and the "gradle-wrapper.jar".
- Modified the LICENSE file to match the stock LICENSE. Added a note that normalize.css is MIT licensed.
- Updated the top level README to include an explicit section for build instructions. It just points to the "developing myriad" document so that users don't struggle to find out where the build instructions are located.

This closes: #49
Review: #49