Ignore semver errors on packages

With `npm-me shama` I hit:

```shell
TypeError: Invalid Version: 0.4.0a
    at new SemVer (/usr/local/lib/node_modules/npm-me/node_modules/semver/semver.js:273:11)
    at SemVer.compare (/usr/local/lib/node_modules/npm-me/node_modules/semver/semver.js:312:13)
    at Function.compare (/usr/local/lib/node_modules/npm-me/node_modules/semver/semver.js:493:31)
    at /usr/local/lib/node_modules/npm-me/index.js:17:25
    at Array.sort (native)
    at /usr/local/lib/node_modules/npm-me/index.js:16:33
    at Request._callback (/usr/local/lib/node_modules/npm-me/node_modules/npm-stats/node_modules/nano/nano.js:291:11)
    at Request.self.callback (/usr/local/lib/node_modules/npm-me/node_modules/npm-stats/node_modules/nano/node_modules/request/index.js:142:22)
    at Request.emit (events.js:98:17)
    at Request.<anonymous> (/usr/local/lib/node_modules/npm-me/node_modules/npm-stats/node_modules/nano/node_modules/request/index.js:856:14)
```

as invalid versions were used at one point in time. This just ignores those packages. Thanks!