BUG: Add SparseArray.all
- [x] closes #xxxx
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

This is the part of https://github.com/pandas-dev/pandas/pull/17386.
`Block.where` uses `ndarray.all`, but there is no such method in `SparseArray`.
This makes that `all` evaluates `SparseArray([False, False, True])` as `True`.
https://github.com/pandas-dev/pandas/blob/master/pandas/core/internals.py#L1400