Improved docker handling (clean up / pulling )

Fix global setup (#17)

* Remove all Zemu containers before each test suite is run.
Remove all Zemu containers on SIGINT signal.
Fix elf path on dir binding.

* Pull bolos-emu image if not available.

* Minor text output optimization.

* Set timeout for containers kill.
Minor code cleanup.

Support for custom functions

v0.0.7

allow passing custom functions

Support for X11 User interface

v0.0.6

add support for X11/Qt UI

Improved logging

v0.0.5

allow passing directory and image filename

Improved app path issue

v0.0.4

path resolution should not be done in zemu

Improved start/close times

v0.0.3

reduce start up time

Initial release

v0.0.2

fix ci config