Disable AC_GNU_SOURCE
Don't pass environment unless sudoing, update libc++ flags.
Disable boost-no-exceptions.
Tweak parameterization.
Merge pull request #151 from evoskuil/version2

Fully-generated Travis build matrix.
Declare NOMINMAX in VS props to avoid std::min/max conflics.
Un-reverse the bitcoin_hash type in memory

With this change, the reversal only takes place in the encode_hash
and decode_hash functions.