added support for protoc plugins
use --plugin arguments to locate plugin executables instead of modifying PATH
Added support for protoc plugins that are written in Java and deployed as Maven artifacts.
fixed typo
Added support for plugin arguments and JVM options
javaHome is now located via jdk toolchain if available
small logging changes
Bumped version number to 0.3.5-SNAPSHOT
Added documentation for descriptor set output and protoc plugins.
changed version back to 0.3.0-SNAPSHOT
Merge pull request #9 from rwicke/plugin-support

Added support for protoc plugins