Switch from rev-list --count to shortlog -s to count commits (TriBITS #45)

It turns out that the --count argument to git rev-list is not support in git
1.7.0.4.  The behavior of the code is that it was just returning empyt for the
number of commits.  That is bad!  Therefore, I changed to using 'git shortlog
-s HEAD ^<tracking_branch>' as that seems to work.

Build/Test Cases Summary
Enabled Packages: TriBITS
Enabled all Forward Packages
0) MPI_DEBUG => passed: passed=177,notpassed=0 (0.85 min)
1) SERIAL_RELEASE => Test case SERIAL_RELEASE was not run! => Does not affect push readiness! (-1.00 min)
Split lines of shortlog -s on any whitespace (TriBITS #45)

So it turns out that 'git shortlog -s' uses a tab, not a space to separate the
number of commits from the author's name with '<num_commits>\t<author_name>',
not just a space.  This fixes that.

I updated one test to prove that both tabs and spaces work for the split.

Build/Test Cases Summary
Enabled Packages: TriBITS
Enabled all Forward Packages
0) MPI_DEBUG => passed: passed=177,notpassed=0 (0.80 min)
1) SERIAL_RELEASE => Test case SERIAL_RELEASE was not run! => Does not affect push readiness! (-1.00 min)
Merge remote branch 'casl-dev/master'