only supply nonce when a password digest is used to avoid schema validation errors
Fix typo in header, breaking heading.

Noticed in the readme there was a heading that had a + at the start
of the line.  Removed it to fix formatting.
Merge pull request #513 from droppedoncaprica/master

Fix typo in header, breaking heading.
Merge pull request #496 from lsalzman/master

[WS-Security] Only supply nonce when a password digest is used to avoid schema validat...