Fix warnings in podspec

Signed-off-by: Jai Govindani <govindani@gmail.com>
Update Pods

Signed-off-by: Jai Govindani <govindani@gmail.com>
Add support for setting stop view's color

Signed-off-by: Jai Govindani <govindani@gmail.com>
Bump version to 0.3.1

Signed-off-by: Jai Govindani <govindani@gmail.com>