Remove Config#Refresh

Because it has been removed from libgit2:
https://github.com/libgit2/libgit2/commit/55cb4999720f46eddb97e25e7ddc6ac068dd0bae

(cherry picked from commit 5c72fe54b89c9f400a8d7b87c0d1a689b89b252e)
Add Remote#Ls.

Allow filtering heads by name.

(cherry picked from commit f6fa1a38abf7be7d4546b736e6db1ae7229e972f)