Linux support, auto-ip guessing, Bugfixes

• finally removed any support of dest which has been deprecated since 0.2.x
• Linux support: docker-sync can now also be used under Linux, were it does a fallback to native volume mounts automatically.
• introducing auto-guessing of the sync_host_ip for simultaneous usage of the same docker-sync.yml using d4m, docker-toolbox and others. Just set sync_host_ip: 'auto'
• fixed spaces in ./src lead to issues with unison
• fixed various issues with the installation of 0.3.x
• fixed issues with the new configuration model
• overall making docker-sync more robust and verbose if things are not as intended
• ..more