Tweaks to IR exercise; minor tweaks to PageRank code.
In test cases, removed tmp/ if it exists prior to test.
Merge branch 'assignment-bugfix'
Published version-1.4.12 artifact
shangfu_gmm
Merge branch 'master' of https://github.com/shangfu/Cloud9 into gmm
Upgraded to CDH 4.2.0
Merge branch 'cdh-upgrade' into gmm