vincent: Minor fixes. Move branch switch to a separate commit.

Conflicts:
	slapos/recipe/generic_mysql/mysql.py

Change RewrtireRule in order to generate https url.

Add zope-username and zope-password options into the recipe erp5_bootstrap.
'zope-username' and 'zope-password' are harcoded on the buildout-side,
because the (https) 'zope-url' no longer include these informations.

(cherry picked from commit 9b3092348a4056e4c19caf4be01220d76da9fdbb)

(cherry picked from commit 2c9dfd0b732d24d5fa3adf99fd337ac45d8fec66)

(cherry picked from commit b2b7a123ebed4d962b08b6a1fd8565d5d66195b3)

Noticed by Benjamin.
(cherry picked from commit e51770f440db737f4904a24cb4d3180d422b0702)