Code cleanup
Return -1 when failed to publish message
Merge pull request #1158 from hurtonm/master

Code cleanup
Note that ZMQ_TCP_ACCEPT_FILTER is deprecated
Added AppDynamics as corporate author
Problem: ZMQ_CURVE_SECRETKEY reads beyond end of Z85 data

Solution: change setsockopts on printable keys to expect 41, nor 40
bytes. Code still accepts 40 bytes for compatibility, and copies the
key to a well-terminated string before using it.

Fixes #1148
Reworking Travis script
Minor changes to Travis CI script
Cleaned up test_xpub_nodrop

Renamed test case to actually explain what it's testing, and cleaned up
the code a little.
Merge pull request #1151 from hintjens/master

Documentation patches
Bugfix wrong CMakeLists.txt after rename of file
Merge pull request #1159 from kreuzberger/master

Bugfix wrong CMakeLists.txt after rename of file
Reset metadata for outbound messages
Merge pull request #1161 from hurtonm/master

Reset metadata for outbound messages
Add const qualifier to source parameters in zmq_z85_decode and zmq_z85_encode
Merge pull request #1162 from xaqq/encode_decode

Add const qualifier to source parameters for z85 encode/decode
Code cleanup
Merge pull request #1163 from hurtonm/master

Code cleanup