Prepend 'reproman-' to the AWS EC2 instance names

[chaselgrove]

Using repronim environment names for EC2 instances means that names that make sense for repronim (e.g. "aws") can be unhelpful in the EC2 console. Prepending 'reproman-' to the EC2 name is an indication that the instance belongs to reproman.

[codecov[bot]]

Codecov Report

Merging #533 into master will decrease coverage by 5.98%. The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master     #533      +/-   ##
==========================================
- Coverage   89.75%   83.76%   -5.99%     
==========================================
  Files         148      148              
  Lines       12483    12487       +4     
==========================================
- Hits        11204    10460     -744     
- Misses       1279     2027     +748     

Impacted Files	Coverage Δ
reproman/resource/aws_ec2.py	66.15% <75.00%> (+0.28%)	:arrow_up:
reproman/resource/tests/test_ssh.py	27.53% <0.00%> (-72.47%)	:arrow_down:
reproman/support/jobs/tests/test_orchestrators.py	26.71% <0.00%> (-68.57%)	:arrow_down:
reproman/support/jobs/orchestrators.py	47.23% <0.00%> (-47.04%)	:arrow_down:
reproman/interface/tests/test_execute.py	71.84% <0.00%> (-28.16%)	:arrow_down:
reproman/support/jobs/submitters.py	54.25% <0.00%> (-25.00%)	:arrow_down:
reproman/resource/ssh.py	75.00% <0.00%> (-14.17%)	:arrow_down:
reproman/interface/execute.py	86.62% <0.00%> (-8.29%)	:arrow_down:
reproman/tests/skip.py	93.25% <0.00%> (-4.50%)	:arrow_down:
reproman/resource/tests/test_session.py	97.24% <0.00%> (-2.30%)	:arrow_down:
... and 5 more

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[yarikoptic]

Sounds like a good idea, and we do something like that for e.g. credentials stored by datalad. I looked through other backends and insofar I think this is a unique case. Let's proceed