prepare for the release
[maven-release-plugin] prepare release v0.5.0
[maven-release-plugin] prepare for next development iteration
update Spark Compatibility in doc
Update docs with new tachyon jar paths
update docs for running mr
reference tachyon-client instead of tachyon
Grammar fixes

Mostly these are small wording changes and some more detailed
explanations in a few areas.
Merge pull request #285 from manugoyal/upstream-branch-0.5

Grammar fixes
minor documentation fix
prepare 0.5.0 release again
Merge branch 'branch-0.5'