Interface Initialization & Reload Data

### Interface Initialization
Added initializer so that the line chart could be added via Storyboard (in addition to programmatically). Now uses both `initWithFrame:` and `initWithCoder:`, as opposed to only `initWithFrame:`. This allows the graph to be setup completely in the interface. The `delegate` property was also changed to an `IBOutlet` so that it could be set from the interface (it can still be set programmatically too).

### Reloading Data
Added new `reloadGraph` method. This new method will reload the data source of graph, and all of its properties. This allows for more dynamic graphs that change after they've been created. The `reloadGraph` method is almost identical (in functionality) to the UITableView method `reloadData`.

### Sample App
The sample app has been updated to reflect the changes made above. In the update sample app, the graph is setup using the interface. A *Refresh* button and *Refresh Settings* have also been added to exhibit the capabilities of the `reloadGraph` method.

### Documentation
Also made documentation improvements. Regular code comments have been converted to documentation comments. Plus, improvements have been made to the `Readme.md` to describe (in better formatting and detail) how BEMSimpleLineGraph works.

### Note on File Duplicates
While reviewing the pull request you may notice that a substantial number of files were deleted. Don't worry though, nothing really got deleted. I simply removed duplicate files and then relinked everything in Xcode. So now when you modify the files in the sample app, you don't need to copy the changes to the external folder (or vice versa). Now there's only one file to change, not two.

### A BIG Thanks
And thank you for this fantastic project! This is definitely one of **the best line graph** projects available on GitHub, or anywhere. Thanks for project and the work that you put into it. I'll be using it in one of my upcoming apps! Keep it up!