Fix template marker to be consistent with comments

During the switch to HStringTemplate in the Battery module,
the "percentage" marker was changed to "percent", which
seems like a typo to me, as the documentation is still
referring to "$percentage$".
Fix default format string for `batteryBarNew`

This format string seems to have been missed when switching to
HStringTemplate.
Merge pull request #50 from ibab/master

Two small fixes to the Battery Module