Implement Series.copy

[itholic]

Implement Series.copy and add Examples to Frame.copy also

>>> s = ks.Series([1, 2], index=["a", "b"])
>>> s
a    1
b    2
Name: 0, dtype: int64
>>> s_copy = s.copy()
>>> s_copy
a    1
b    2
Name: 0, dtype: int64

[codecov-io]

Codecov Report

Merging #869 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #869      +/-   ##
==========================================
+ Coverage   94.27%   94.27%   +<.01%     
==========================================
  Files          34       34              
  Lines        6201     6202       +1     
==========================================
+ Hits         5846     5847       +1     
  Misses        355      355

Impacted Files	Coverage Δ
databricks/koalas/missing/series.py	100% <ø> (ø)	⬆️
databricks/koalas/frame.py	95.94% <ø> (ø)	⬆️
databricks/koalas/series.py	95.34% <100%> (+0.01%)	⬆️

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[softagram-bot]

Softagram Impact Report for pull/869 (head commit: 42bd618)

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💡 Insights

• Co-change Alert: You modified frame.py. Often test_dataframe.py (koalas/tests) is modified at the same time.

📄 Full report

• Permalink: Full report for pull/869

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[ueshin]

LGTM.

[ueshin]

Thanks! merging.

[itholic]

@ueshin Thanks :)