fix Master key generation based on https://en.bitcoin.it/wiki/BIP_0032
"Use IL as master secret key, and IR as master chain code."

IL was being used for chain code and IR was being used from master secret
* using compressed point when building address
* added bip32 tests
added test vector 2, fix derivation function
test for edge cases when deriving (IL >= n, ki = 0, Ki = INFINITY)
Merge pull request #2 from elmato/master

master secret / master chain using inverted part of HMAC-SHA512, added private derivation