maktaba#library#Require doesn't respect names from addon-info.json

Maktaba has trouble consistently reading the right plugin names from addon-info.json for some functions like `maktaba#library#Require`. If you have a library plugin that looks like

```
somedirname/
somedirname/addon-info.json <-- contains {"name": "mylib"}
somedirname/autoload/mylib.vim
```

and you execute

``` VimL
set rtp+=path/to/somedirname
call maktaba#library#Require('mylib')
```

the Require call will fail saying mylib was not found.

Calling `maktaba#plugin#Detect()` will fix this, but maktaba ought to be able to detect the right plugin name without it.