Update release notes for 1.14

Pinging @larkost and really everyone else. This is almost entirely from the closed tickets on the 1.14 milestone excluding bugs that seemed like they never made it into releases, but there are likely things missed and/or things that should be excluded. I tried to mention the bits of backward incompatibility in the "Compatibility" block.
No, it isn't. #2762 makes all binary formats return as ReQL native rather than raw; this makes `http` return whatever it fetches from the remote URL as a binary object. (I'm going to change it to "a binary object," though, which is more accurate than "format." And has an article.)