[SPARK-5296] [SQL] Add more filter types for data sources API

This PR adds the following filter types for data sources API:

- `IsNull`
- `IsNotNull`
- `Not`
- `And`
- `Or`

The code which converts Catalyst predicate expressions to data sources filters is very similar to filter conversion logics in `ParquetFilters` which converts Catalyst predicates to Parquet filter predicates. In this way we can support nested AND/OR/NOT predicates without changing current `BaseScan` type hierarchy.

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Author: Cheng Lian <lian@databricks.com>

This patch had conflicts when merged, resolved by
Committer: Michael Armbrust <michael@databricks.com>

Closes #4623 from liancheng/more-fiters and squashes the following commits:

1b296f4 [Cheng Lian] Add more filter types for data sources API