Added new slug extensions

Update to allow {category} and {author} in urlFormat. Can also specify
slug as {slug}
Added new slug extensions

Update to allow {category} and {author} in urlFormat. Can also specify
slug as {slug}
Merge branch 'master' of https://github.com/MacsDickinson/Sandra.Snow

Conflicts:
	src/Snow/Extensions/SlugExtensions.cs
updated barbato dlls to contain snow update
filter private posts from the overall list
exclude non-published posts from the series data
Merge pull request #74 from MattsGitCode/master

Private posts are still generated
Merge pull request #72 from MacsDickinson/master

Added new slug extensions
Improved view error message output
Merge pull request #77 from thecodejunkie/improved-error-messages

Improved view error message output
fix relative urls in RSS feed
added check to ensure urls with http are excluded
opps, added support to exclude https too
Merge pull request #78 from phillip-haydon/Issue#76

Make URLs in RSS feed absolute so images show