Change error handling for gist tag: raise exception
fix tests for new behaviour
Change error handling in 'post_url' tag: raise exception
raise exceptions in include tag
'gist' tag: switch to ArgumentError exception class

SyntaxError is reserved for Ruby's internal use.

Adjust the tests, including the call to liquid to
make it rethrow ArgumentErrors.
Print server address when launching a server.

Related to: https://github.com/mojombo/jekyll/issues/1583
adds more information to the documentation of generators
Merge pull request #1590 from fxn/master

adds more information to the documentation of generators
Update history to reflect merge of #1590
Autoload yaml files under _data directory

The jekyll engine will autoload all yaml files(ends with .yml or .yaml)
under _data. If there's a file members.yml under the directory, then user
can access contents of the file through site.members.
Merge pull request #1586 from mojombo/print-webrick-url-if-muted

Print server address when launching a server.
Update history to reflect merge of #1586
Merge pull request #1003 from liufengyun/data-sources

support data sources
Update history to reflect merge of #1003
Merge pull request #1514 from maul-esel/tag-errors

Consistent error handling in Liquid tags
Update history to reflect merge of #1514
Add docs for new Data Files feature
Fix typo in data docs; update section pagination for migrations to correctly point back to data
Rebase on upstream/master; rename file to work with docs_ul includes file
another pass on the documentation of generators

This commit refines the docs contributed in f074bb6.