Add support multi zeo servers.
Add read only fallback
add changes
add docs for multipe zeo addresses and read-only-fallback.
Merge remote-tracking branch 'github/master'

Conflicts:
	CHANGES.txt
Add support multi zeo servers.
Add read only fallback
add changes
add docs for multipe zeo addresses and read-only-fallback.
Merge branch 'master' of github.com:pretaweb/plone.recipe.zope2instance

Conflicts:
	CHANGES.txt
Fix the current tests by adding default value for read-only-fallback.
Add read-only-fallback to true test
Add multiple zeo addresses test
Add travis badge in readme file.
Merge pull request #12 from pretaweb/master

Add support for multiple zeo servers inc readonly fallback