frontend: Reduced banner image sizes

Down from 87.7 to 69.6 kB (- 18.1 kB / 20.6 %)
Removed "Add new club member" feature

All registered users should be registered properly with a password.
We have the (co)pilot_name columns now for listing names of unregistered
passengers etc.
tests: Fixed broken test_auth.py
Merge pull request #248 from Turbo87/remove-unregistered-pilots

Removed "Add new club member" feature
frontend/templates: Removed broken link
commands/tracking: Use aerofiles library to export IGC files from tracking
Merge pull request #249 from Turbo87/tracking2igc

Export Live Tracking as IGC files
map.css: add missing position and overflow attributes

They got lost somewhere in the past.
js/flight: Added map.hover_enabled flag
js/flight: Added baro.hover_enabled flag
js/flight: Added basic playback functions
js/baro: Added click support

This is not influenced by the hover_enabled flag and can be used
in playback mode
js/flight: Added Start/Stop button
js/flight: Check global_time value explicitly

This makes the playback compatible with the live tracking pages
css/ol-PlayButton: Added z-index

This puts the play button behind the layer switcher
Merge pull request #251 from Turbo87/play

Playback function for flights
fabric: Adding fabric v1.8.2 to developer requirements file
fabric: Added basic fabfile

This requires that the developer has setup a "skylines" host in his
SSH config file (`~/.ssh/config/`)
fabric: Call restart.sh in repo folder directly

.. and do the git reset call
fabric: Moved instructions from restart.sh into the fabfile