Expose option to adjust icon scale parameters

[LukasPaczos]

We could expose options for icon scale parameters to make it more customizable.

[DejanRistic]

@LukasPaczos I'm curious if this made it to the latest snapshot build on sonatype? i'm on 0.6.0 and i'm not seeing the scale options yet.

https://oss.sonatype.org/content/repositories/snapshots/com/mapbox/mapboxsdk/mapbox-android-plugin-locationlayer/

[LukasPaczos]

Thanks for pointing that out @DejanRistic! Targeting the issue in #556, up-to-date snapshots should be available within minutes.