Bump release to 1.9.0

[jmaupetit]

Added

• Improve Arrow 0.15.0 support after changes in arrow.get() behavior (ArrowParseWarning, for the .get() method #296)
• Watson now suggests correct command if users make small typo (Enable git-like did-you-mean feature #318)

Changed

• Always show total time at bottom of report (Total time information #356)
• Use the default system newline character for CSV output (Avoid dubble newlines in csv output #366).

Fixed

• Stylize prompt to create new project or tag (Stylize prompt for new project and tags #310).
• Aggregate calculates wrong time if used with --current (aggregate calculates wrong time if used with --current #293)
• The start command now correctly checks if project is empty (Fix #321 #322)
• Aggregate ignores frames that crosses aggregate boundary (Aggregate doesn't seem to work with frames that cross day boudaries #248)
• The report and aggregate commands with --json option now correctly encode Arrow objects (The report and aggregate commands with --json option don't work any more #329)