Allow limit to equal zero

It's reasonable for the number of resources to be set to zero. (The limit could later be increased once resources are available, for example.)

Fix travis CI

v2.4.1

Remove old go versions from travis

Support go modules

v2.4.0

fix import path

Fix a possible deadlock when Acquiring/Releasing different weights

2.3.0

Init go mod.

Fix race condition resulting in hung Acquire()

2.2.0

Update travis settings

2.1.1

Minor fixes

2.1.0

Optimize cycle in Acquire

2.0.0

awesome go badge

1.2.0

Fix case when released more then acquired.

1.1.1

Fix go vet warnings in tests and up coverage to 100