Merge pull request #12 from eccyan/features/fix_for_old_apis Fix for using old APIs.
Merge pull request #11 from eccyan/features/fix_if_present Fixed ``ifPresent```` throws 'Sequence contains no elements' when empty
Merge pull request #7 from eccyan/features/optional_has_observable Version 1.1.0
set version
updated change log
added developer information
initial commit