Replaced ELCImagePicker => GMImagePicker

[hanssens]

In short, this is a severe refactoring which basically replaces the ELCImagePicker with the GMImagePicker in order to support lacking iOS 8 features with the first.

Effort has been put into this by @MrBasque, @micheladrion and @hanssens.

Features & Improvements

• Supports iOS 8 Photos Framework, incl. shared albums and non-local photos (optimized cloud storage)
• [IOS] Fixes issue Selecting photos from a Shared Album results in 'null' wymsee/cordova-imagePicker#56: Selecting photos from a Shared Album results in 'null'
• [IOS] Fixes issue Unselectable photos and empty albums when Optimized Storage is enabled wymsee/cordova-imagePicker#57: Unselectable photos and empty albums when Optimized Storage is enabled
• [IOS] Enables fetching of images on-demand that aren't stored locally
• [IOS+Android] Response now returns both original image path but now also the thumb path as well
• No further clientside/consumer impact

Ground breaking changes

• Removed ELCImagePicker in favor of GMImagePicker
• Supports iOS 8 Photos FrameworkOnly support for iOS 8

Known issues

• Fetching duration of an image from iCloud (on-demand) can range from a second to a couple of seconds
• Could seriously use a codereview