Qt metrics v0.15: Bug fixes and coding improvements

Project dashboard: Corrected a case where Autotest section didn't
list the failed tests correctly (case when only one to list).

Filter box: Corrected layout problem where certain IE and Mozilla
versions showed the selection boxes like 'stairs'.

Coding style improvements: Replaced database column constants with
variables as they may change in different queries. Created a function
for creating build number string for the build links (instead of using
same piece of code in several files).

Change-Id: I473ff4994ece0c016b6ad4fd578fb8ebaa5d5d84
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>