Documentation typo fix
Added scalar tests
Documentation update
Fix is.named() so it handles NA names correctly

Addresses issue #19.
Tests for code in assertions.r
Back to roxygen2 4.0.2
Changed is.named logic re NA names

Now returns FALSE, not TRUE, in that situation. See pull request #20.
Merge pull request #20 from bpbond/master

More test code; minor fixes to is.named() and documentation