Merge pull request src-d#578 from erizocosmico/perf/reduce-gc-press

packfile: improve performance a little by reducing gc pressure

Merge pull request src-d#567 from strib/avoid-revlist-when-deleting

remote: avoid expensive revlist operation when only deleting refs

transport: fix ssh override config, fixes src-d#519

Merge pull request src-d#485 from mcuadros/fetch-tags

remote: fetch, correct behavior on tags

Merge pull request src-d#444 from silvertern/gitignore-ch2

Fixes checkout not possible with (untracked) files under gitignore

Merge pull request src-d#400 from ajnavarro/improvement/diff-delta

format/packfile: improve binary delta algorithm

removing import rule, to try to get godoc running

fix travis

fixtures: initialize fixtures into separated methods (src-d#214)

To be able to use fixtures with other test frameworks than go-check,
we created two methods, one to set fixtures path correctly, and
another to remove all the temporal data created when testing.

fix plumbing/difftree package name (src-d#191)