Fix typos and messages

Fix some typos (depending, preferences), uniformity on chapter
references, and examples (objective vs nominative)
Update English cases

Added subjective, changed from genitive to possessive, fixed another
typo (on runtime, at runtime)
Merge pull request #5 from flodolo/master

Fix typos and text on l20n.org
Bug 874375 - Add LICENSE file. r=mathjazz
Bug 888372 - Update L20n.org to L20n 1.0 beta3. r=mathjazz