Merge pull request #61 from matthayes/master

Coalesce should merge types where possible, add EmptyBagToNull
Add BagGroup UDF and tests
Merge pull request #63 from william-g-vaughan/master

Add BagGroup UDF and tests
Merge pull request #62 from matthayes/master

Add EmptyBagToNullFields
Updates to what's new

[ci skip]
SampleByKey no longer requires a salt for randomization
updated bug URL in readme
Merge pull request #64 from samshah/master

SampleByKey no longer requires a salt for randomization
Update README

[ci skip]
Update README

[ci skip]
 Updating doc for SampleByKey
Merge pull request #65 from evionkim/master

 Updating doc for SampleByKey
Doc update

[ci skip]
Bump version to 1.0.0

[ci skip]
Add note on compatibility

[ci skip]
Released 1.0.0, therefore bumping version

[ci skip]
README update

[ci skip]
Update contributors

[ci skip]
add SimpleRandomSample to sampling, which implements a scalable simple random sampling algorithm
Merge pull request #66 from mengxr/master

add SimpleRandomSample to sampling, which implements a scalable simple random sampling algorithm