Add some macros

These were written by Will Vaughan.  Just checking them in.

I added several unit tests.  However these can't be run with pig 0.10 due to a bug in importing macros with PigUnit.  This will be fixed by pig 0.11.  For now they are disabled.  However they do pass with a patched pig 0.10.
Remove countByParallel.pig
Merge pull request #26 from william-g-vaughan/master

Add UDFs for weighted sampling of a bag and counting elements of a bag
Add examples
Merge branch 'master' of github.com:matthayes/datafu
Test against pig 0.11
Readme update
Add .travis.yml
Merge branch 'master' of github.com:linkedin/datafu
Merge branch 'master' of github.com:linkedin/datafu
Turn off JvmMetrics log garbage
Remove appenders for root logger to reduce log spam
Update .travis.yml
Update .travis.yml
Update .travis.yml
Update .travis.yml
Remove macros code
Removes macros
Merge pull request #28 from matthayes/master

Logging cleanup
Add build status to README

[ci skip]