move plugin groups to under groups key (#44)

[vegu]

fix #44

[coveralls]

Pull Request Test Coverage Report for Build 216

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 370 unchanged lines in 15 files lost coverage.
• Overall coverage increased (+0.3%) to 70.655%

---

Files with Coverage Reduction	New Missed Lines	%
.tox/py27/lib/python2.7/site-packages/vaping/plugins/command.py	5	0.0%
.tox/py34/lib/python3.4/site-packages/vaping/plugins/command.py	5	0.0%
.tox/py35/lib/python3.5/site-packages/vaping/plugins/command.py	5	0.0%
.tox/py36/lib/python3.6/site-packages/vaping/plugins/command.py	5	0.0%
.tox/py37/lib/python3.7/site-packages/vaping/plugins/command.py	5	0.0%
.tox/py27/lib/python2.7/site-packages/vaping/plugins/vodka.py	7	64.58%
.tox/py34/lib/python3.4/site-packages/vaping/plugins/vodka.py	7	64.58%
.tox/py35/lib/python3.5/site-packages/vaping/plugins/vodka.py	7	64.58%
.tox/py36/lib/python3.6/site-packages/vaping/plugins/vodka.py	7	64.58%
.tox/py37/lib/python3.7/site-packages/vaping/plugins/vodka.py	7	64.58%

Totals
Change from base Build 214:	0.3%
Covered Lines:	6366
Relevant Lines:	9010

---

💛 - Coveralls

[codecov-io]

Codecov Report

Merging #75 into master will increase coverage by 0.25%.
The diff coverage is 82.6%.

@@            Coverage Diff             @@
##           master      #75      +/-   ##
==========================================
+ Coverage   71.33%   71.58%   +0.25%     
==========================================
  Files          16       16              
  Lines         893      901       +8     
==========================================
+ Hits          637      645       +8     
  Misses        256      256

Impacted Files	Coverage Δ
vaping/plugins/command.py	0% <0%> (ø)	⬆️
vaping/plugins/__init__.py	59.33% <100%> (+1.83%)	⬆️
vaping/plugins/fping.py	97.18% <100%> (-0.04%)	⬇️
vaping/plugins/vodka.py	64.58% <77.77%> (-1.38%)	⬇️

---

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