Update tag regex in ReportXINDEXResults function

Update the regex that is used to check if a line has an entry tag.
Instead of checking for only capital letters, check for numbers too.

The current tag check  would find EN but not EN442, both of which are
valid entry tags.

OSEHRA-Id: http://issues.osehra.org/browse/OAT-148
Change-Id: I8fd01d1e25d68340b097f161d464839d5ebb2300