Bug fix, Python version deprecations, build fixes, version 1.0.0

[jantman]

This PR wraps up quite a few changes:

• Fix catch all exceptions when using pip _internal? #7 where certain new versions of pip throw an AttributeError on import if running in Lambda (or other environments where sys.stdin is None).
• Stop testing Python 3.3 and drop official support for it.
• Stop testing Python 2.7 and 3.4.
• Add DeprecationWarnings for any Python version < 3.5.
• Multiple pip10 fixes.
• Test fixes:
  • Always install latest versions of coverage and pytest.
  • Switch docs build to py37
  • Begin testing under py37 and py38

This also bumps to 1.0.0, since this has been working in the wild for quite a few years.

[codecov-io]

Codecov Report

Merging #8 into master will increase coverage by 1.73%.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           master     #8      +/-   ##
========================================
+ Coverage   98.26%   100%   +1.73%     
========================================
  Files           4      3       -1     
  Lines         230    242      +12     
  Branches       39     38       -1     
========================================
+ Hits          226    242      +16     
+ Misses          4      0       -4

Impacted Files	Coverage Δ
versionfinder/versioninfo.py	100% <ø> (ø)	⬆️
versionfinder/version.py	100% <100%> (ø)	⬆️
versionfinder/versionfinder.py	100% <100%> (+2.61%)	⬆️
versionfinder/__init__.py

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