Core: Make page title on member pages unique.

This commit partially reverts r9105, which made the `<title>` element the
same across all member pages, which goes against SEO conventions.

This commit does the following:
* When on a member's landing page (eg. example.com/members/admin/), the page title will be `admin | {SITE NAME}`.

* Uses the profile navigation name in the page title instead of the component's admin title.  For example, when on `example.com/members/admin/profile/`, the page title will be `'admin | Profile | {SITE NAME}'` instead of `'admin | Extended Profiles | {SITE NAME}'`.

* Adds the profile subnav name in the page title when on a member component sub-page. For example, when on `example.com/members/admin/activity/mentions/`, the page title will be `admin | Activity | Mentions | {SITE NAME}`.

Fixes #5838.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9249 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
bp-legacy: Add JS to toggle the "Blog Details" block on registration page.

When theme compatibility was introduced in BuddyPress 1.7, the javascript
to toggle the site registration form fields was not ported over from
bp-default.  This commit brings back this functionality to bp-legacy.

Fixes #5846.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9250 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Blogs: Invalidate total blog count when site is deleted.

This commit:
* Uses `bp_blogs_clear_blog_object_cache()` to invalidate the total blog count after a site is deleted and when a site is created.
* Deprecates `bp_blogs_format_clear_blog_cache()`, a function that isn't used internally as of this commit, for v2.2.0.
* Adds a unit test.

Fixes #6062.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9251 cdf35c40-ae34-48e0-9cc9-0c9da1808c22