Implement API to access wallpaper and watch face properties

[codeanticode]

Need to give access to:

• wallpaper preview state
• wallpaper offsets
• watch face ambient mode state
• watch face screen shape and insets
• watch face special properties

[rijuldhir]

@codeanticode I am interested in contributing to this repo.
I am also a GSoC,17 aspirant. Can you assign me a quick-win/relatively easy issue and help me contribute

[codeanticode]

@rijuldhir Many thanks for your interest and enthusiasm. Here you have some lighter issues you could look at: #21, #303, #253.

Just as a quick comment to better frame your future contributions. We are not really after scoring "winning points" quickly, but rather to engage with people with diverse backgrounds and interests in a project that benefits a large community of users around the world ;-)

[codeanticode]

implemented in d66d4e6