modify cookie[]= to support extra cookie options

Using the syntax `cookie[:key, :options => 'hash']='value'`` will now
merge the provided hash with the existing @options hash (which allows
for changing cookie options on a per-cookie basis).
multi-json implementation
1.8.7 fix
Merge pull request #90 from Ortuna/multi-json

multi-json implementation
Merge pull request #66 from kylewlacy/master

Modify cookie[]= method to support additional options
Reverting due to Ruby 1.8.7 incompatibility

Revert "Merge pull request #66 from kylewlacy/master"

This reverts commit 1ad87b6730064300234c6796f214c9eb8c895efa, reversing
changes made to 21415118af38224ca34948ef0b621b57c1201820.