Shrink the binary

If there is ever a need to run Consul in an environment where storage space is limited we can shrink the binary from its current size (~107Mb) to roughly 15Mb with a few small changes.

* with `-ldflags="-s -w"` flags reduces the size to 78Mb
* with [this diff to remove `go-discover` and the bindata for the UI](https://github.com/hashicorp/consul/compare/dnephin/deprecate-go-discover) using the `-tags=tiny` build flag reduces the size to 49Mb
* with [upx](https://upx.github.io/) compression reduces the size to 15Mb

With additional flags on `upx` that size may be reduced further. These sizes were on `linux/amd64`, I'm not sure how much different that would be for arm.