draft-petithuguenin-behave-turn-uris-08

-  s/eventually/potentially/
-  Changed the ABNF to use references from RFC 3986 instead of
   copying them.
-  Converted the design note about hierarchical parsers into a MUST
   NOT statement.
-  Updated the RFC 6982 forms for Chrome and Firefox.
-  Added text in security section about verifying that username,
   password and uris are received over a secure connection.