Fix multisite bugs & enhance functionality

Bugs fixed:
- saving of settings on the multisite settings page was not working.
- restoring site to default settings from multisite settings page was not working.
- initializing new blogs with settings from a chosen default blog was not working.
- wrong option debug information shown on multisite settings page

Enhancements:
- When using the 'Reset default settings' button on a blog in a network while another blog has been chosen to be used as a basis for the settings for all new blogs, the reset will respect that setting and reset the blog to the settings from the chosen blog.
- For small networks ( < 100 sites ), the network page user interface has been improved, by offering drop-down lists of the blogs for blog selection fields. For larger networks, the interface remains the same.

Also:
- Added a few extra options to the network blog reset/copy exclude list (theme dependent ones)
- clean up wrongly stored options (i.e. wpseo_ms in options table not in sitemeta table)
- made the padding on select boxes slightly smaller as letters were being cut off at the bottom.
Readme props update
Improved injecting of settings from a default blog to new blogs

This wasn't always working well with the new auto-options logic.
It should now work as expected for multisite individual activations, network activations, new blogs on the network.

The only case in which it will not always work well is with multisite and WPSEO in the must-use directory.
Added note to admin page about not importing privacy sensitive options and such
Updated network page text - site not blog
Small textual changes
Fix for weird failing unit test
Make sure the plugin (de-)activates on all blogs when being network activated
Darn typo ;-)
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into Issue-935-multisite

Conflicts:
	readme.txt
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into Fix-fail-unit-test
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into Issue-935-multisite
Merge branch 'Fix-fail-unit-test' into Issue-935-multisite
Fix tests failing on breadcrumbs class

- Better tests
- More defensive coding in breadcrumb class (only needed for the unit tests as in normal circumstances the global post object will always be available)
Commented out problem test as it seems to give different results on different PHP versions
Merge pull request #1273 from jrfnl/Issue-935-multisite

Fix multisite bugs & enhance functionality