Make it installable with a single go install line

[cirosantilli]

Not sure how Go does things, but it would be great to have a one liner go install-like thing that gets you the latest release along:

go install github.com/mdawsonuk/LevelDBDumper@latest

That attempt fails with:

go: github.com/mdawsonuk/LevelDBDumper@latest: module github.com/mdawsonuk/LevelDBDumper@latest found (v2.0.2+incompatible), but does not contain package github.com/mdawsonuk/LevelDBDumper

as of e750a27ff58443ecc410b5c16abbdc539d617387