Add license to gemspec

This silences the warning during builds:

  WARNING:  licenses is empty

Signed-off-by: Greg Hurrell <greg@hurrell.net>
Apply minor grammar fix to docs

Signed-off-by: Greg Hurrell <greg@hurrell.net>
Include autoload file in vimball archive

This was missing from the 1.9 release.

Fixes:

  https://wincent.com/issues/2175

Signed-off-by: Greg Hurrell <greg@hurrell.net>
Update docs for 1.9.1 release

Signed-off-by: Greg Hurrell <greg@hurrell.net>