MUMMNG-409
UP-3811 Add merging person dir DAO and clarify docs

Don't want to add custom attribute sources to the list of DAOs in
the cascading DAO. I.e. the existing comments in
personDirectoryContext.xml gave one the wrong idea.

This commit wraps the cascading DAO in a merging DAO and updates
comments to strongly suggest adding custom sources to the latter
rather than the former.

This is a cherry-pick and re-word of
67612e9794051fc3cfa7d0303f6b85b8a140fd9c from ssp-master.
UP-3835: Adding DB Module, Updating all uportal packaged modules and portlets that require the db drivers to leverage the new module
UP-3835: Removing unneeded ant calls to build war for uportal-db module, adding module to parent, adding more explicit examples of the db drivers from the uPortal manual, Removing dependency management section from uportal-db pom
Merge pull request #166 from shawnconnolly/UP-3835

UP-3835: Adding DB Module
Merge pull request #167 from mindblender/master

UP-3719 Added adjustments to clean up some of the missing fluid styles.
UP-3719 minor cleanup of respondr pull request
UP-3719 fix missing quote
UP-3836: Reworking javascript to look more correct and function in Respondr
UP-3825: Partial update to buttons to make the text black
Merge pull request #169 from shawnconnolly/UP-3825

UP-3825: Partial update to buttons to make the text black
Introduce the management of an alternative maximized link in portlet
parameters named 'alternativeMaximixedLink', also modify universality and
muniversality themes to use this parameter and to open such links in a
new browser tab.
UP-3755 : Adding i18n text translation missing on href title
NOJIRA Updated comment for log file format for logback
Merge pull request #168 from shawnconnolly/UP-3836

UP-3836: Reworking javascript to look more correct and function in Respondr
UP-3843 : Fixed aggregation error for search aggregation trying to submit null when someone searches for a space.
Updating Backgrounds Portlet Preference to have methods for thumbnails
Adding UI changes for Background Preferences Portlet
UP-3841, UP-3842 : Adding Background Preferences thumbnails and configuration
Merge pull request #164 from dmccallum/UP-3811-merging-vs-cascading-pd-daos

UP-3811 Add merging person dir DAO and clarify docs