Asset serialization debut

Some assets serialization tests.
.Obj serialization and load is effective but need a lot of improvment (serialized files are actually to big) #28
This work'll be continue later when serialization on components will be effective and when team will be agree about assets data structure.
There is no boost dependencies. It only use cereal ( https://github.com/USCiLab/cereal )
Download the last cereal on development branch and paste /include/cereal in vendors folder.

Actually with serilized .obj : 
File size is multiplied by 2.5 but loading time is divided by approximatively 10.

Bullet source has been updated, I'm sorry of that.

Glm has been updated to last version, it should not cause any problem.