Update README.md

Fixed typos.
Add failing test for calling template with empty string as content.
Fix protocol implementation to work with empty strings.
Merge pull request #14 from walterrw/fix/empty_string_exception

Fix exception thrown when calling a template: Cannot create node from ""

Sorry for the delay on this, thanks for the fix and tests!
Merge pull request #13 from malcolmsparks/patch-1

Update README.md