unit test for model/bundle loading

[jaimejiyepark]

Test_Bundle.swift

• pulled allll the little local variables out and created them into a member of this class to examine if the guard statements work.
• I initialized them all to nil and compiled (a boolean to see if the model will compile) to false to compare the before and after when calling these guard statements.
• the func compiled_model also sets all the member variables and is used to compare to the individual setting functions

Test_Case

• Every test begins with an empty bundle and a filled bundle (filled with compiled_model). The empty objects are tested in the beginning to see if they're truly empty, if they're still empty with an improperly set, if the tested property is filled, and if it matches the filled bundle's property.

[kingst]

#shipit, love seeing some more unit tests