add travis-procedure to project.
adjust flags (-Wgnu).
force travis build on mac os x.
require strptime for linux as well.
add both test statuses to readme.
change ordering for shell libs and add linktargets.
link shell callbacks to shell-cmds and timeslot

Should fix the problems with building on linux,
which seem to be based in weak-linking.

Also link sqlite into database.
actually use c-flag and avoid initializer warning

Manually set the empty shell_tuple explicitly.
fix build-status badges in readme.
we can rely on cmake being installed on travis

See https://github.com/travis-ci/travis-ci/issues/2540 for
more information.