* dvc: get rid of is_walking_tree
No longer needed. Some applications of `isinstance()` will be refactored
in the future, as trees will just provide the needed functionality.
* dvc: move GitTree to dvc/tree/
* dvc: rename *RemoteTree to *Tree
Usually we need it to parametrize tests with, so there is no
reason to duplicate the code. I've left `local_remote` fixture
just because it is so convenient and often used in a lot of tests.
* pylint: enable attribute-outside-init check
* fix tests
* Fix mock for time
This was an interesting one. I was mocking `time` on function definition
and then, using those later on test run. When all the tests were run, there
would be some delay that'd make tests fail. Hmmm ...
Ruslan Kuprieiev
Saugat Pachhai