Fixed missing optional cases as well as creating a common trait
for readMessage[?] usage.
Merge pull request #47 from cideas/extendable-fix

Fixed missing optional cases as well as creating a common trait
rename Option -> OptionValue so it doesn't shadow scala's builtin Option type.
Merge pull request #52 from robey/options

rename Option -> OptionValue
oops, forgot the tests.
factor out file reading, process imports, and pass them to the generator.
process imported symbols during generation.
use collectFirst and do not use string interpolation.
optimize map/getOrElse.
code golfing.
add a test to verify that imported protos from other packages are fully qualified.
Merge pull request #54 from robey/imports

fix protobuf "import" symbol names
Improved UpdateTestResources:

- generates parsed .txt files with camelCased names
- general code improvements
Updated generated tests.

Generated scala class file names now match their outer Java class names.
Fixed the generated UsesImportedPackage in UpdateTestResources.
update protobuf version to latest (2.5.0).
add parseFrom() methods to the generated object, to mirror static methods created by protobuf.
fix tests for added "parseFrom" methods.
if an error occurs during compilation, exit with an error code, so external tools will know.
Merge pull request #56 from robey/parsefrom

add "parseFrom" and exit(1) on error