Fix to compile package with GHC 7.6.1

Issue reported by Eugene Kirpichov <ekirpichov@gmail.com>.
Port tests to binary >= 0.6.0.0.
Make tests compile with GHC 7.6.1 too.
Bump version to 0.2.
Add getLazyByteString.

Don't allow block merging for this function, as
blocks are always done on strict bytestrings.