Update LogDog client library to generate URLs.

Update the LogDog client library to generate LogDog stream viewer URLs.
This includes:
- Capturing the LogDog Coordinator host from the enviornment via
  bootstrap.
- Implementing full stream paths and URL generation.
- Adjusting the StreamClient implementations to retain the prefix and
  coordinator host values.
- Wrapping text/binary StreamClient file descriptors in a container to
  expose per-stream higher-level functionality.

Tests have also been updated to assert the new functionality.

TBR=nodir@chromium.org
BUG=chromium:659291
TEST=unit

Review-Url: https://codereview.chromium.org/2453273002
NOKEYCHECK=True
GitOrigin-RevId: a32ab2fad3bda41efae1607ec66be78f48a9d0b9
6 files changed
tree: 9b608a64e1b13d57abf343ef282bbee745d96af1
  1. tests/
  2. __init__.py
  3. bootstrap.py
  4. stream.py
  5. streamname.py
  6. varint.py