Remove hard-coded use of main class in ivory script

This was broken in 0fa22ddbb587be1f350cd34e895d859c2f0684c7
because setting mainClass in assembly is not enough.
It's better to specify this directly in the build anyway.

http://www.roman10.net/specify-the-main-class-in-a-jar-file-for-hadoop/

> If a jar file contains a main class specified in its manifest file,
> hadoop will take the main class even if the command specify another main class.
Merge pull request #89 from ambiata/cofarrell/ivory-main-class

Remove hard-coded use of main class in ivory script
Remove now redundant mainclasses.json config.
Merge pull request #90 from ambiata/topic/remove-mainclasses

Remove now redundant mainclasses.json config.
Add bin/build for branch builds
Merge pull request #73 from ambiata/cofarrell/ci-manual-publish-branch-builds

Add separate bin/build script for branch builds
Reduce jar size and include a stripped proguard binary.
Revert logging.
Remove duplication in depend.scala, added ThrownExpectations.
Merge pull request #86 from ambiata/topic/jarsize

Reduce jar size and include a stripped proguard binary.
Extract declation of CompressionCodec in cli and make optional via env
Pass CompressionCodec through to HdfsDirectEavtTextImporter
Pass CompressionCodec through into Recompress
Remove --no-compression from ingest-bulk command
Merge pull request #94 from ambiata/topic/codec-consolidation

Extract declation of CompressionCodec in cli and make optional via env
Update saws to 6c1bfce (including exclusion of joda-time wildcard)
Merge pull request #92 from ambiata/topic/saws-update-fast-sbt

Update saws to 6c1bfce (including exclusion of joda-time wildcard)
Update mundane to 1.2.1-20140708033412-e6bdaf5
Add thrift definition for Dictionary
Remove name from Dictionary