Report for Golang errors (securego#284)

* Report for Golang errors

Right now if you use Gosec to scan invalid go file and if you report the result in a text, JSON, CSV or another file format you will always receive 0 issues.
The reason for that is that Gosec can't parse the AST of invalid go files and thus will not report anything.

The real problem here is that the user will never know about the issue if he generates the output in a file.

Signed-off-by: Martin Vrachev <[email protected]>

Build the code sample for string builder only fron Go 1.10 onwards

Update README

Merge pull request securego#219 from ccojocar/goreleaser

Use the goreleaser tool to perform releases