* Make /api/v1/timelines/public and /api/v1/timelines/tag/:id public
Fix #1156 - respect query params when generating pagination links in API

* Apply pagination fix to more APIs

make status pagination headers generation more lax about next page
existing

to only those from local users; Add link to "extended information" to
getting started in the UI; Add defaults for posting privacy; Change
how publish button looks depending on posting privacy chosen

redis-backed "mentions" timeline as redundant (given notifications)

from accounts/tags because it's a terribly inefficient way to paginate
large sets of data

resources that require a user context vs those that don't (such as public timeline)

/api/v1/statuses/public   -> /api/v1/timelines/public
/api/v1/statuses/home     -> /api/v1/timelines/home
/api/v1/statuses/mentions -> /api/v1/timelines/mentions
/api/v1/statuses/tag/:tag -> /api/v1/timelines/tag/:tag