Add support for nameHashing and recompileOnMacroDef options.

Add support for two new incremental compiler options introduced in
sbt 0.13.2:

  * `nameHashing` which enables new, experimental incremental compilation
    algorithm
  * `recompileOnMacroDef` which controls heuristic related to how
    macro definitions and their dependencies are handled

Note that since `recompileOnMacroDef` is turned on by default we introduced
`recompileOnMacroDefDisabled` command line option which changes the
default value to be off.
Merge pull request #42 from gkossakowski/name-hashing

Add support for `nameHashing` and `recompileOnMacroDef`
update README: Zinc builds with sbt 0.13 now
Merge pull request #43 from gkossakowski/patch-1

update README: Zinc builds with sbt 0.13 now
Migrate to non-deprecated constructor of CompileSetup.

The sbt/sbt#1122 and sbt/sbt#1125 introduced additional argument
(nameHashing flag) to CompileSetup and deprecated the old constructor.
Let's catch up with this change in zinc now.
Merge pull request #45 from gkossakowski/compile-setup

Migrate to non-deprecated constructor of CompileSetup.
Use Scala 2.11.0-RC3 in scriptit tests.

Switch to Scala 2.11.0-RC3 running scriptit tests. Also, update
scala/2.11/jars/test to use full version number for Scala 2.11.0-RC3.
The reason we need to switch to full version is change in sbt's definition
of binaryVersion that scriptit uses. In sbt 0.13 all Scala milestones and
release candidates are considered to be binary incompatible hence
binaryVersion is a full version number.

This has been missed during upgrade to sbt 0.13 of zinc.