create a docker image to build and run iris

[kimberlythegeek]

• write a Dockerfile to build iris-core
• use the docker image for running linting and tests in Travis
• update all documentation and usage instructions
• verify integration with iris_firefox and update usage documentation

[mwobensmith]

Got it to run once we put in the missing step:

Xvfb :99 -screen 0 1920x1080x24+32 +extension GLX +extension RANDR > /dev/null 2>&1 &

Now what we have are some warnings/errors:

Xlib.xauth: warning, no xauthority details available
Xlib.xauth: warning, no xauthority details available
Xlib.xauth: warning, no xauthority details available
Xlib.xauth: warning, no xauthority details available
/bin/sh: 1: xset: not found
Cannot run Iris because CAPSLOCK is on. Please turn it off to continue.
Failed platform check, closing Iris.

The xset program is required to be able to query the locked keys on the keyboard. We need to find out why it's not available. There is the workaround of passing -n for now but we'll have to fix this somehow.