linter issues

[avereha]

I think those are real issues, disabling the linter for now so we can start using it:

cache/cache.go:191:10: Error return value of `m_.Set` is not checked (errcheck)
                        m_.Set(&memcache.Item{
                              ^
We can add metric for this.

cache/cache.go:167:5: ineffectual assignment to `cacheErrs` (ineffassign)
                                cacheErrs = cacheErrs + "; " + res.err.Error()
                                ^
This is a bug.
blocker/requestblocker.go:104:18: Error return value of `yaml.Unmarshal` is not checked (errcheck)
                        yaml.Unmarshal(fileData, &rc)
                                      ^
bug?
blocker/configfile.go:46:9: G306: Expect WriteFile permissions to be 0600 or less (gosec)
        err := ioutil.WriteFile(cf.blockRuleConfigName, output, 0644)
               ^
bug?

Making this issue so we remember to back to this.