Compile on save + report syntax errors

Addressing #10, one thing tho is that this PR doesn't handle `_test` files which should trigger `go test` instead of `go build`.
![main_go_-__users_mattetti_code_golang_src_bitbucket_org_mattetti_ricard](https://f.cloud.github.com/assets/113/2370980/c57893a0-a819-11e3-8b1e-a919b67a3fd3.png)

I built this PR based on the work done in #9 (support for gofmt/goimports)