Adds nomad monitor command. Like consul monitor, this command allows you
to stream logs from a nomad agent in real time with a a specified log
level

add endpoint tests

Upgrade go-hclog to latest version

The current version of go-hclog pads log prefixes to equal lengths
so info becomes [INFO ] and debug becomes [DEBUG]. This breaks
hashicorp/logutils/level.go Check function. Upgrading to the latest
version removes this padding and fixes log filtering that uses logutils
Check