Stop leaking routerinfos that are rejected due to keypinning
When we added the keypinning code to dirserv_add_descriptor, we forgot to free rejected routerinfos.
We should backport this to 0.2.9, because it is the earliest version run by the public directory authorities. (And it's LTS.)
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information