Added comments for MainActivity class
Secure tethering wifi hotspot

User can create secure tethering wifi hotspot now.
Added more comments.

In future, we will give option to user : create secure or public wifi hotspot.
Removing unnecessary images
New cleaner and better UI

User can select security type - NONE or WPA PSK
Show password checkbox
Merge branch 'ssid_password' to master

Conflicts:
	app/src/main/java/com/mokani/tethering/app/MainActivity.java