[ADAM-502] Add missing Long implicit to ColumnReaderInput

Fixes #502
Merge pull request #504 from laserson/ADAM-502

[ADAM-502] Add missing Long implicit to ColumnReaderInput
[ADAM-505] Removed `adam-local` from docs
Merge pull request #507 from laserson/ADAM-505

[ADAM-505] Removed `adam-local` from docs
[ADAM-499] Add -onlyvariants option to vcf2adam

Fixes #499.
Merge pull request #501 from laserson/ADAM-499

[ADAM-499] Add -onlyvariants option to vcf2adam
[ADAM-489] Moved Spark and Hadoop to provided dependency.