Bug fixing for hasnans when non-DoubleType.

[itholic]

ks.Series.hasnans and ks.Index.hasnans seems not work properly for non-DoubleType.

>>> ks.Series([True, True, np.nan]).hasnans
Traceback (most recent call last):
...
pyspark.sql.utils.AnalysisException: cannot resolve 'isnan(`0`)' due to data type mismatch: argument 1 requires (double or float) type, however, '`0`' is of boolean type.;;
'Aggregate [max((isnull(0#12) OR isnan(0#12))) AS max(((0 IS NULL) OR isnan(0)))#21]
+- Project [__index_level_0__#11L, 0#12, monotonically_increasing_id() AS __natural_order__#15L]
   +- LogicalRDD [__index_level_0__#11L, 0#12], false

This PR fixed it.

[ueshin]

Otherwise, LGTM.

[HyukjinKwon]

Looks good except https://github.com/databricks/koalas/pull/1681/files#r463261346