Merge pull request #68 from shivaram/master

Delete temporary files after they are used
Makefile: factor out SPARKR_VERSION to reduce potential copy&paste error; cp & rm called with -f in build/clean phase; .gitignore includes checkpoints and unit test log generated by run-tests.sh
Update Makefile (style uniformity)

Add a space for style uniformiity
Merge pull request #72 from edwardt/master

(minor improvement) Use variable for SparkR assembly versioning in Makefile; ignore folders and files generated in unit tests to avoid accidental checkins
add links to devtools and install_github
Update Makefile (style uniformity)

Add a space for style uniformiity
Update README.md
Add where to enter bugs ad feeback
don't check in gedit buffer file'
Update README.md

rewording and remove some unnecessary sentence
Update README.md

further rewording per comment feedback
Update README.md

Add blank lines for better seperations
Update README.md

Move feedback toend of doc
Merge pull request #76 from edwardt/addjira

Add links to jira in README
Fix a bug that modifications to build.sbt won't trigger rebuilding.
Merge pull request #78 from sun-rui/master

Fix a bug that modifications to build.sbt won't trigger rebuilding.