Snapchat class --> Object

Snapchat class should be used as an object instead of being filled of
static methods.
New method to check if it can be downloaded
A lot of changes

Too much to describe here. @hatboysam I have done pretty much all of
your request.

Logic changes :
- Public methods start with a capital letter
- Private methods are grouped together
- Private static methods are grouped together

Some changes :
- Made private what had to be.
- Created better and easier methods for Sending Snap, Video or Stories.
- Better way to get Friends, Stories, Snaps,..
- Reduced the amount of time JSON was parsed.
- Much more.
Fix java convention mistakes

I mixed the convention of C + + and Java
Update README.md + 1 refactoring

Due to the big changes I have made, the README.md had to be updated.
Update README.md (2)
Merge pull request #10 from jamesst20/master

Huge refactor