Set the row.names by the first non-short length

Before this was always using the first length, which resulted in the
data.frame being truncated if the first argument was a length 1 vector
to be recycled.

Fixes #680
Add note to news
Simplify logic for NA length
context is not capitalized
Add a few more data_frame tests

This is mostly to get Travis to retry the build.
Fix extraneous parenthesis.
Extra whitespace

hopefully travis will run correctly this time :-/
Merge pull request #681 from jimhester/data_frame_truncation

Data frame truncation - Set the row.names by the first non-short length.

Closes #680