Version 1.9.0

New functionality

• Support User defined variables and expressions.
• Add async parameter to upload params(#63)
• Add expired_at parameter to private download. (#60)
• Add moderation parameter in explicit call (#59)

Other changes

• Fix double encoding for commas and slashes in text layers (#66)
• Add artistic filter test (#65)
• Add gravity-auto test (#64)
• Fix OutOfMemoryError when uploading large files in android. Fixes #55 (#57)
• Fix encoding error in api update resource (#61)