Option to load multiple language files

With this commit, multiple language files can be set for loading. If
only a string is passed to langFile, then only this one language file is
loaded. However, if an array is passed, multiple language files will be
loaded. Each language file must be as a string in this array.
Load the custom 404 page the same way as normal controller method
Use method for lang prefix instead of class
Merge branch 'develop' of github.com:slax0rr/BaseController into develop
Update readme
Merge branch 'develop' of github.com:slax0rr/BaseController into develop