Bug 8938: Transport cost matrix script and template contain untranslatable strings

This patch fixes the problem reported.

To test:
1) Apply the patch
2) Update translations for your preffered language, xx-YY
3) Check new entries
egrep -Rn "Cost must be expressed as a decimal number|Invalid value for" misc/translator/xx-YY*
4) Check no regression on alert, go to
Administration > Transport cost matrix
Edit some value and put a negative value & save,
alert must show up
5) On errors, part of the error string is now on TT file,
no regressions expected here

Verified that changes appear in translated language (de-CH) as appropriate. No regressions found by testing en en de-CH.
Signed-off-by: Marc Véron <veron@veron.ch>

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Tested both, entering a numeric value < 0 and non-numeric values, no regressions found.
Passes tests and QA script.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>