Resolving testing issues

[whart222]

Fixes: NA

Summary/Motivation: Resolves testing issues with YAML loading and subprocesses

Changes proposed in this PR:

• Explicit specification of the loader for YAML tests. This eliminates a deprecation warning and insures that the tests are safe.
• Eliminating deprecation warnings for pyutilib.subprocess tests
• Configure pyutilib.subprocess tests to not use a shell process. This ensures that the bash environment is not corrupted during testing execution (esp. with nose).

Legal Acknowledgement

By contributing to this software project, I agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[coveralls]

Coverage decreased (-0.2%) to 62.26% when pulling 335444e35bb06459c48ca77e302671960798b9c4 on safe_yaml into cc1a6176a3ae184273f5fa3cbf1c89262bd2bc5f on master.

[codecov-io]

Codecov Report

Merging #53 into master will decrease coverage by 0.19%. The diff coverage is 0%.

@@            Coverage Diff            @@
##           master      #53     +/-   ##
=========================================
- Coverage   63.29%   63.09%   -0.2%     
=========================================
  Files          87       87             
  Lines        8688     8691      +3     
=========================================
- Hits         5499     5484     -15     
- Misses       3189     3207     +18

Impacted Files	Coverage Δ
pyutilib/subprocess/processmngr.py	62.02% <0%> (-3.38%)	:arrow_down:

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