Display Hebrew month days in Hebrew letters, not numbers.

This pull request modified luach.js so that the Hebrew month days will be displayed as Hebrew letters, not numbers. This has the advantage that it is very easy to distinguish between the gregorian month days and the Hebrew month days.
I am not a Java/Web programmer at all, but given google/stackexchange and my present C/C++ knowledge, it was easy to change. I don't know, however, if it is OK to put Hebrew letters directly in the code, or should have I entered those via \uXXXX notation.

Note that I haven't tested this change directly. I created this change directly on Kaluach's Firefox plugin, and patched this single line change into this repository.