change version range for requests dependency

[yangaws]

…nd docker

Issue #, if available:
If requests==1.12.4 is installed, import sagemaker will get version conflicting error since docker-compose and docker-py requires different version range of requests. To avoid this, we'd better set the version constraint here (at least temporarily)
docker-compose requires https://github.com/docker/compose/blob/master/setup.py#L36
docker-py requires https://github.com/docker/docker-py/blob/master/setup.py

Description of changes:
Require requests module to have version in the intersection of what docker compose and docker-py require.

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[codecov-io]

Codecov Report

Merging #533 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #533   +/-   ##
=======================================
  Coverage   92.76%   92.76%           
=======================================
  Files          71       71           
  Lines        5348     5348           
=======================================
  Hits         4961     4961           
  Misses        387      387

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[laurenyu]

😭