Implement DataFrame.query

[itholic]

This PR proposes to implement DataFrame.query

>>> df = ks.DataFrame({'A': range(1, 6),
...                    'B': range(10, 0, -2),
...                    'C C': range(10, 5, -1)})
>>> df
   A   B  C C
0  1  10   10
1  2   8    9
2  3   6    8
3  4   4    7
4  5   2    6

>>> df.query('A > B')
   A  B  C C
4  5  2    6

The previous expression is equivalent to

>>> df[df.A > df.B]
   A  B  C C
4  5  2    6

For columns with spaces in their name, you can use backtick quoting.

>>> df.query('B == `C C`')
   A   B  C C
0  1  10   10

The previous expression is equivalent to

>>> df[df.B == df['C C']]
   A   B  C C
0  1  10   10

[codecov-io]

Codecov Report

Merging #1273 into master will decrease coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1273      +/-   ##
==========================================
- Coverage   95.14%   95.11%   -0.04%     
==========================================
  Files          35       34       -1     
  Lines        7202     7219      +17     
==========================================
+ Hits         6852     6866      +14     
- Misses        350      353       +3

Impacted Files	Coverage Δ
databricks/koalas/missing/frame.py	100% <ø> (ø)	⬆️
databricks/koalas/frame.py	96.55% <100%> (-0.14%)	⬇️
databricks/koalas/usage_logging/__init__.py	97.29% <0%> (ø)	⬆️
databricks/koalas/usage_logging/usage_logger.py	100% <0%> (ø)	⬆️
databricks/conftest.py	96.22% <0%> (ø)	⬆️
databricks/koalas/__init__.py	85.1% <0%> (ø)	⬆️
databricks/koalas/namespace.py	87.87% <0%> (ø)	⬆️
databricks/koalas/plot.py	94.28% <0%> (ø)	⬆️
databricks/koalas/testing/utils.py	78.51% <0%> (ø)	⬆️
... and 4 more

---

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 8556443...8300045. Read the comment docs.

[HyukjinKwon]

Looks good otherwise.

[itholic]

@HyukjinKwon Thanks for the review!