2.0.0-beta.0

Note: This is a beta release and most likely will have have some instability and/or regressions.

Changes:

• (feature, privacy) #21 - Use macOS CoreLocation for geolocation;
• (bug) #24 - App should notify only about the newest available update;
• (bug) Update checker was scheduled twice;
• (feature) allow user to choose between old geolocation (1.1.0 and earlier) and macOS CoreLocation,
• log debug information when macOS CoreLocation is used,
• (bug) #26 - notify only about updates that satisfy installed version according to semver - stable version won't notify about prereleases,
• (ui, feature) enhance how percentage of norm value is displayed next to PM2.5 and PM10,
• (ui, feature) norm percentages are now colorized from green to dark red according to norm thresholds,
• (ui) #23 - adjust font so newer macOS uses San Francisco, thanks @thymikee
• cleanup measurement components,
• upgraded from electron 1.8.2 to 1.8.3,