Dvc

1. Added `dvc pipeline show` for showning pipeline stages for target stage.
2. Bug fixes for our tests.

1. Added support for Microsoft Azure Blob Storage. Kudos c-w and EricSchles.
2. Fixed a bug with non-deterministic md5 computation for directories.
3. Added support for dvc gc -c|--cloud to collect remote garbage.

1. Bugfix for improper usage of logger.debug() in _read_metric().
2. Bugfix for `dvc metrics show` in binary packages caused by the bug in ply module.

1. Bugfix for the improper comparison of versions in updater.
2. Bugfix for the output of `dvc metrics show` without `all-branches`.

1. Support for LOCAL/S3/GS/SSH/HDFS external dependencies, outputs and cache.
2. Misc bug fixes and performance improvements.
3. Added `-c|--cwd` option for `dvc repro` to change directory before reproduction. Similar to `make -C`.
4. Added `-p|--purge` option for `dvc remove` to remove the dvc file.
5. Introduced `dvc import` to import external files and track them as dependencies.
6. Added `-m|--metrics` option for `dvc repro` to output metrics after reproduction.
7. Added `-d|--default` option for `dvc remote add` to set remote as a default one.
8. `Data cloud` is now included into `Remote` class. All remote drivers for local/s3/gs/hdfs/ssh are now located under dvc/remote/. New remote types are easy to add.
9. Added `--all-branches` option for push/pull/fetch/gc to operate on cache for all present branches.
10. Introduced `dvc move` to allow renaming data files added with `dvc add`.
11. Introduced `dvc lock/unlock` to lock/unlock dvc files from reproduction.
12. Added support for a list of cache types. E.g. `dvc config cache.type reflink,copy`.

1) Bug fixes;
2) Added `dvc install` for installing git post-checkout hook;
3) Support `dvc checkout` for a single file;
4) Support for reflink/hardlink/symlink/copy types of cache links;
5) Support for configurable and shareable cache dirs;
6) Stages without dependencies are now ran by `dvc repro`;
7) Dvc now checks for updates once a week and prints a warning if newer version is available;