Add failing testcases for btc_to_satoshi
Consolidate the amount parsing/formatting code
Change encode_hex to take a data_slice
Clean up some minor things

* Simplify operator <<
* Do not pass data_slice by reference
Merge pull request #141 from libbitcoin/cleanup

Cleanup
Merge pull request #143 from evoskuil/version2

Build secpk256k1 from libbitcoin fork.
Merge remote-tracking branch 'libbitcoin/amounts' into version2

Conflicts:
	test/amount.cpp