HTTP: Don't force cookie values to be urlencoded because it breaks usage of...

HTTP: Don't force cookie values to be urlencoded because it breaks usage of cookies in some scenarios like the LiveJournal Importer. Instead add a filter for a plugin to use if it really wants to have the cookie mangled. Fixes #19922 props pw201, dllh and kurtpayne. 


git-svn-id: https://core.svn.wordpress.org/trunk@20372 1a063a9b-81f0-0310-95a4-ce76da25c4cd