Modified the organization of the overview section and tried to make the section on the API configurations clearer.
Encode unsafe HTML chars in string values during serialization

This helps Express State protect against XSS attacks if untrust user
input it passed to `expose()` without being escaped first.

Fixes #11
Cache the unsafe-html-chars regex and enhance XSS unit test
Merge branch 'master' of github.com:zhouyaoji/express-state into zhouyaoji-master
Tweak updates to README and add a HISTORY entry
Fix typo in README
Add "Untrusted User Input" section to README
Merge branch 'escape-html'

Conflicts:
	HISTORY.md