Made OTContract::GetIdentifier(OTString&) non-virtual.
Removed unused Base64 functions in OTCrypto.
Added -Woverloaded-virtual to PEDANTIC_CXX_FLAGS
Merge pull request #286 from benma/cleanup

Removed unused (and hidden) base functions
README: Add license badge
Merge pull request #289 from lclc/readme

README: Add license badge
git hook: use printf for diff pritn out

Clang-format diff is not written out correctly if the code contains '\n'. The new line is interpreted by echo.