Update NEWS

Workaround for weird threading issue on Linux

See #327

Add test for seeking

bump version

Fixed httpuv is on CRAN now

Wording

Lets just stick with the versioning scheme

Fix NEWS

Rename 'content_type' to just 'type'

Because 'content_type' may result in partial matching when people try or get the 'content'.
Fixes #169

Update vignette