Create test_NA
Update test_NA
rewrite test_NA
add some tests
Merge branch 'master' of https://github.com/davharris/testdat

# By David J. Harris
# Via David J. Harris
* 'master' of https://github.com/davharris/testdat:
  rewrite test_NA
  Update test_NA
  Create test_NA
Merge pull request #12 from davharris/master

crude test for NAs