Cherry-pick(s): Bugfix multi-line chart and icon + unit test

[kristw]

Cherry-pick the following commit(s):

SHA	Time	Log	Author
1d7f4f2	Tue Aug 14 10:48:21 2018 -0700	[bugfix] line_multi chart crashed on chosen (apache#5568) (apache#5572)	[Krist Wongsuphasawat]
ad469c7	Mon Aug 6 17:27:48 2018 -0700	Fixed the wrong icon for Source -> Table (apache#5574)	[Conglei]

@graceguo-supercat @michellethomas @john-bodley @williaster

[codecov-io]

Codecov Report

Merging #87 into airbnb-master will decrease coverage by 13.97%.
The diff coverage is 28.57%.

@@                Coverage Diff                 @@
##           airbnb-master      #87       +/-   ##
==================================================
- Coverage           77.2%   63.22%   -13.98%     
==================================================
  Files                 45      351      +306     
  Lines               8856    22042    +13186     
  Branches               0     2470     +2470     
==================================================
+ Hits                6837    13936     +7099     
- Misses              2019     8094     +6075     
- Partials               0       12       +12

Impacted Files	Coverage Δ
superset/connectors/sqla/views.py	70.47% <ø> (ø)	⬆️
superset/assets/src/explore/visTypes.jsx	57.14% <ø> (ø)
superset/assets/src/visualizations/line_multi.js	0% <0%> (ø)
...sets/src/explore/components/DisplayQueryButton.jsx	84.74% <100%> (ø)
.../src/dashboard/components/RefreshIntervalModal.jsx	86.95% <0%> (ø)
superset/assets/src/logger.js	95.23% <0%> (ø)
...src/explore/components/controls/VizTypeControl.jsx	89.58% <0%> (ø)
superset/assets/src/visualizations/word_cloud.js	0% <0%> (ø)
superset/assets/src/components/ActionMenuItem.jsx	0% <0%> (ø)
...et/assets/src/visualizations/deckgl/layers/arc.jsx	0% <0%> (ø)
... and 300 more

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