bugfix,init page object's lexed attribute.

the page object's attribute 'lexed' is not correctly inited.so when
use page.lexed to generate the search index file,nothing will be
indexed.
Merge branch 'master' of github.com:GitbookIO/gitbook into fork

Conflicts:
	lib/parse/page.js
Fix #491: handle correctly url without path for links
Bump version to 1.3.1
Merge pull request #489 from codepiano/fork

bugfix,init page object's lexed attribute.
Adapt new page.parse api for tests
Remove unnecessary option "repo" from tests
Update README.md

Hi, i add 2 new plugins for gitbook, I hope it will be useful to someone.
Merge pull request #495 from romanlytkin/patch-1

Update README.md