Initial proto-type to use RE2 regex library

Using patched version of John Millikin's haskell-re2:
https://github.com/ryo1kato/haskell-re2/commit/9863f24e25f94b311c286c4f77a97c35ac3a4053

--color doesn't work because it has a dummy implementation for this commit.
implement --color for RE2, using Regex.RE2.replaceAll
first prototype with blaze-builder (Note: exit code is always True)
Use blaze-builder for output, fixes #14

Note blaze-builder is merged to bytestring hence used
Data.ByteString.Builder