add git-lfs support (#1056)

* add mistyping support for git lfs

* add the rule

* fix flake8

* flake8

* add to readme

* use fixtures and regex

* get rid of additional matched strings

tests/rules/test_git_lfs_mistype.py

@@ -0,0 +1,29 @@
+import pytest
+
+from thefuck.rules.git_lfs_mistype import match, get_new_command
+from thefuck.types import Command
+
+
+@pytest.fixture
+def mistype_response():
+    return """
+Error: unknown command "evn" for "git-lfs"
+
+Did you mean this?
+        env
+        ext
+
+Run 'git-lfs --help' for usage.
+    """
+
+
+def test_match(mistype_response):
+    assert match(Command('git lfs evn', mistype_response))
+    err_response = 'bash: git: command not found'
+    assert not match(Command('git lfs env', err_response))
+    assert not match(Command('docker lfs env', mistype_response))
+
+
+def test_get_new_command(mistype_response):
+    assert (get_new_command(Command('git lfs evn', mistype_response))
+            == ['git lfs env', 'git lfs ext'])