Fix permalink sending

[lencioni]

Commit 81460d2 added the sending of permalink to Akismet by adding it to the list of "default mappings" all of which get comment_ prepended. However, according to the Askismet documentation1, it appears that they expect permalink to be simply permalink and not comment_permalink.

This commit fixes this discrepancy by moving the :permalink symbol from the list of attributes that receives the prepended comment_ to the list of attributes that does not receive this prependage.

[ehoch]

Woh, you seem quite correct on this one. No idea why the Akismet guys didn't catch this when I had them looking over my requests! I'll try and get this one merged this week. Thank you!