Enable creating Index from list like 'Index([1, 2, 3])'

[itholic]

Resolves #948

>>> Index([1, 2, 3])
Int64Index([1, 2, 3], dtype='int64')

>>> Index(list('abc'))
Index(['a', 'b', 'c'], dtype='object')

[codecov-io]

Codecov Report

Merging #986 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #986      +/-   ##
==========================================
+ Coverage   94.84%   94.84%   +<.01%     
==========================================
  Files          34       34              
  Lines        6519     6522       +3     
==========================================
+ Hits         6183     6186       +3     
  Misses        336      336

Impacted Files	Coverage Δ
databricks/koalas/indexes.py	96.73% <100%> (+0.1%)	⬆️
databricks/koalas/series.py	96.3% <0%> (-0.02%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update feca119...a060210. Read the comment docs.

[softagram-bot]

Softagram Impact Report for pull/986 (head commit: a060210)

⭐ Change Overview

(Open in Softagram Desktop for full details)

📄 Full report

• Permalink: Full report for pull/986

Impact Report explained. Give feedback on this report to [email protected]

[ueshin]

LGTM.

[ueshin]

Thanks! merging.

[itholic]

@ueshin Thanks :)