CMake: used ZMQ shared lib for opentxs shared lib

In the switch to use the system's libzmq we preserved the
statically linking of it. But since all other library dependencies
are linked as shared libraries libzmq should be as well.
Then, third party library linking is consistent when building our
own shared library.
Merge pull request #6 from toxeus/sharedZMQ

CMake: used ZMQ shared lib for opentxs shared lib
Generated new AWS S3 deployment secret key after re-fork of repo.
CMake: fix include workaround for OS X
Merge pull request #9 from murrekatt/develop

CMake: fix include workaround for OS X
Removed Windows warning about GCC pragma
Fixed crash in OT-Armor decompression when trying to decompress plaintext
Removed unused parameter from OT_Command::details_refresh_nym
Aligned colons in output in MadeEasy::stat_asset_account
Fixed several functions that return an amount to return OT_ERROR_AMOUNT
 instead of -1 which could be a valid amount.
 This was an artifact of the conversion from string to int64_t.
Merge pull request #10 from toxeus/bug_fixes

Bug fixes
travis: install new CMake on OS X

Before, the attempt to install a new version of CMake with Homebrew
failed because there already was an installed CMake version.
Merge pull request #14 from toxeus/travisPath

travis: install new CMake on OS X
Delete unused fast_mutex.h