progress

- modified loading page transition logic;
- add challenge page;
- improved step counting algorithm;
- fixed a bug which may cause a continuous crush by adding a network
connection checking mode;
- add some animations to specific views;
- add some images;
-
Merge branch 'master' of https://github.com/Leongum/ExRunner

Conflicts:
	RevolUtioN/PopTrack-Info.plist