lock down sbt version
src/main compiles with either
lets factorize the creation of inversion failures so we can swap out the impl if we decide to change types
this implicit injection should be applicable to eithers of any left type
Danger, Will Robinson, an exception may be thrown here
introduce InversionFailure as its own type
Left(InversionFailure()) -> InversionFailure.failedAttempt(failed)
allCatch.either {...} -> attempt(x){...}
fix tests
fix up json injection tests
maintain support for conversions that result in options
unsafe get on bufferables
Merge branch 'develop' into either_injections
Adds bijection from BigInt to BigInteger
Add java Base64 from Apache commons
Merge pull request #122 from twitter/bigint-bij

Adds bijection from BigInt to BigInteger
Merge pull request #123 from twitter/base64-depclean

Add java Base64 from Apache commons
Either -> Try
Merge pull request #120 from softprops/either_injections

Either injections
Merge branch 'develop' into no-fn

Conflicts:
	bijection-core/src/main/scala/com/twitter/bijection/Injection.scala