Update lock file to use 2.0 GA gems

Fixes elastic#4098

Add changelog entry for 2.0.0-rc1

Fixes elastic#4081

Added note about beats

Fixes elastic#4062

new lock file for 2.0.0.beta2

Fixes elastic#4038

Update to changes in 2.0 beta1

Fixes elastic#3928

Restore rack dependency because http input needs it

Fixes elastic#3634

Bump version to 1.4.4

Fixes elastic#3624

Update lock file to use 1.5.3.snapshot2

Update lock file for 1.5.3.snapshot1

Fixes elastic#3597