added support for running only specific tests of a test case
fixed test for duplicate register

it should fail w/o force flag and succeed with force flag
more tests

added tests for failing standby register on master, w/o existing
schema (i.e. no master register has been done) and existing schema but
no master entry in table
bugfix: don't use $version unless you localized it by argument
tests for master register
new helper function: move_path moves a path to another on a node
tests for standby promote
bugfix: do not use hard coded data directory
redirect outout to logfile
a revamped version of start/stop postgres
added helper for checking if a program has running process
slightly modified behavior of test cases

Now we always remove the data directories and recreate them before every
test case. This ensures weird follow-up errors because we always have a
defined state
tests for standby follow
tests for witness create
fix: redirect output for check_file_exists()