Enum fixes
Options for GsonEnumHelper package.
Options for enum base class.
Using same names for Java fields as pro to message fields, but prepending _ to names that happen to be Java keywords.
Generating GsonHelper based on package path.
Exposing only protobuf-defined fields for gson
Added more config options.
Merge branch 'gson_enum_conv'

Conflicts:
	src/main/java/com/google/code/proto/gcless/GeneratorConfiguration.java
	src/main/java/com/google/code/proto/gcless/MemlessGenerator.java
	src/main/java/com/google/code/proto/gcless/ProtobufField.java