Close connection when adbd connection is closed

This will ensure the message processor is correctly terminated and
a new connection is established when the adb server process on the
host opens a connection to us again.

debian: update changelog

Build debs also during our travis job

Add kernel patches to add namespace support to binder

Ensure anbox can be properly started by a systemd --user instance

Import helper cmake script to find GMock and GTest on more modern systems

Taken from https://code.launchpad.net/~cmake-extras/cmake-extras/trunk

Some humble suggestions from a lover of language

This gives us all necessary things like DISPLAY or XAUTHORITY within
the environment for a service started by systemd --user

Add in-snap path to nvidia driver binaries to LD_LIBRARY_PATH

Update README.md