2.6.8 - reconnect improvements.

Changed the reconnect logic so it does not try to connect to a server that it just lost the connection to.

With the randomization algorithm, there's a chance the client will immediately try the server it just lost connection with. Move the last connected server to the end of the list when reconnecting.

• [FIXED] - #309 - Removed some debug printf statements
• [CHANGED] - Allow disable reconnect buffer by using size of zero
• [CHANGED] - Added option to set the max unsent size at the writer and fail or discard messages
• [CHANGED] - Updated build.gradle to not fail if TRAVIS_BRANCH isn't set