Added a variable to also allow one to overwrite the git-buildpackage options. If variable not set it just falls back to the original options.
replace signal numbers in trap with their according signal names

Get rid of:

| possible bashism in source/build-and-provide-package
| line 41 (trap with signal numbers):trap bailout 1 2 3 3 6 9 14 15
Drop "possible bashism" from source/git/post-receive

The checkbashism warning is not really true:

| possible bashism in source/git/post-receive line 55 (test -a/-o):if [ -n "$1" -a -n "$2" -a -n "$3" ]; then

but let's get rid of it anyway...
tap_tool_dispatcher: ignore .git directory as well

Stuff like:

| possible bashism in source/.git/hooks/update.sample line 40
| (test -a/-o):if [ -z "$refname" -o -z "$oldrev" -o -z "$newrev" ]; then

is pointless.
tap_tool_dispatcher: use .tap suffix for output files

See https://issues.jenkins-ci.org/browse/JENKINS-15813 ->

| If the file type is considered as binary by Jenkins webserver
| then the TAP plugin doesn't consider this file for inclusion in
| TAP reports. This can be quite confusing and if you're not aware
| of this issue it can easily hide problems.

So don't use just "$filename" but always "$filename.tap" instead.