Add option to specify index_page

Fix redirect to index_page creation for subdirs

Redirect attempts to access directories to index_page

Add tests
Merge pull request #631 from arr2036/master

Fix redirects to index_pages for subdirs
Allow the sidebar side to be specified
Merge pull request #632 from arr2036/master

Specify the sidebar side
Merge branch 'master' into cosmetic_fixes
Merge branch 'master' into codemirror-integration

Conflicts:
	lib/gollum/wiki.rb
Merge branch 'master' into citation-support
Merge branch 'citation-support' into mygollum

Conflicts:
	lib/gollum/wiki.rb
Merge branch 'codemirror-integration' into mygollum
Merge branch 'cosmetic_fixes' into mygollum