Update PrimitiveFieldType.java

Add support of UTF-8!
For i18n (eg. TTS).

"A string must always contain UTF-8 encoded or 7-bit ASCII text." https://developers.google.com/protocol-buffers/docs/proto#scalar

"unicode strings are currently not supported as a ROS data type. utf-8 should be used to be compatible with ROS string serialization. " http://wiki.ros.org/msg

but it works. (testing with python)
Update PrimitiveFieldType.java

add symmetric encoding transformation (serializer/deserializer)
Update PrimitiveFieldType.java

Code Refactoring
Update PrimitiveFieldType.java

Remove dead code
Update PrimitiveFieldType.java

Change parameter of constant
Update RawMessageSerializationTest.java

Add the message serialization tests for UTF-8.
Update RawMessageSerializationTest.java

Raw format style.
Update PrimitiveFieldType.java

Clean code
Merge pull request #19 from Theosakamg/master

Update PrimitiveFieldType$STRING.java for UTF-8