[FEATURE] Integrate config.pageTitleSeparator

Adds a Typoscript option to make the the separator string that is
used between the site title and the page title configurable.

Change-Id: I8fd088ee15d09a0c2414d48d30058c2ed85a1b98
Resolves: #17030
Releases: 4.7
Reviewed-on: http://review.typo3.org/7041
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter