Update README.md

adding some more instructions to README
changing the sweeper job to use SchemaValidator to determine if the key is compatible with topics schema.
updating avro version
Update the RelaxedAvroKeyOutputFormat based on Avro 1.7.7 method signature
Merge remote-tracking branch 'upstream/master'
Fix the offset calculation, we don't use beginOffset anymore
Add classpath/classloader debugging on avro classes
Add classpath debugging for avro classes for sweeper
Merge pull request #115 from HenryCaiHaiying/master

Classpath debugging info and fix the offset calcuation
Deal with property cache.jar.filter.list can be non-existent
Merge pull request #116 from HenryCaiHaiying/master

Deal with property cache.jar.filter.list can be non-existent
fixing schema projection bug
Merge branch 'master' of https://github.com/linkedin/camus
Merged from upstream