- Lots of formatting fixes
-- Fix use of Markdown syntax within HTML <table> tags. (It doesn't work)
   Mostly affects "required" and "since" emphasizing.
-- Change invalid double forward-slash syntax into double-asterisks.
-- Add header row to a lot of tables
-- Fix broken links
-- Fix command-line and properties formatting, now contained in
   syntax highlighting elements.
-- Fix some tables that had multiple entries per row, e.g. in preconditions.md.
-- Change bullet points in download/index.md to separate sections.
- Fix properties example in Maven index.md
- spring.md - sort the sub-tags in alphabetical order.
- Add info to README.md, on building the site locally using Jekyll.
Fix issue where code example text would escape from its div in Firefox 26.0.
(Chrome would just wrap the text.)
Add info to databases.md on support for less common databases, that were
formerly supported as part of Liquibase core.
- Remove XML v2 example from databasechangelog.md, seemed pointless as the
  only difference was the XSD URL.
- Changed XSD v3.0 to v3.1 in databasechangelog.md.
- Removed list of old XSDs from databasechangelog.md, since it also appears in
  the xml_format.md page.
- Add Liquibase 3.1 XSD to the list of XSDs on xml_format.md.
Add a note that preconditions at the changelog level apply to all changesets
within a changelog, not just the file that contains the precondition.
Change reference of v3.0 XSD to v3.1
Add info on the special preconditions comment for Liquibase-formatted SQL.