* Updates docs for CameraPreview, Base64ToGallery and Developer.MD
-DEVELOPER.md: Corrects 'npm run tslint' instruction to 'npm run lint'
-CameraPreview: Fixes syntax error in hide
-Base64ToGallery: Adds desc of options obj props
* Fixes resolveLocalFileSystemURL bug in File.readAsText() and adds File.readAsDataUrl()
- File.readAsText(): window.resolveLocalFileSystemURL() was incorrectly implemented
* Updates callback arg in File.checkFile()
Callback arg of window.resolveLocalFileSystemURL was fileSystem, but it actually returns fileEntry
* Corrects repo link and comments out setFlashMode()
- Repo prop and link in desc were not pointing to the same gh repo as the plugin
- setFlashMode() is not currently available in the repo that gets pulled by the corodova plugin
-DEVELOPER.md: Corrects 'npm run tslint' instruction to 'npm run lint'
-CameraPreview: Fixes syntax error in hide
-Base64ToGallery: Adds desc of options obj props
