v0.6.1 bug fixes

fix: nightscout status check failing due to malformed user settings
fix: null values for serialised status items
fix: TZ date formats not good for some browsers, TZ format made to use a colon ie -0800 is now -08:00
fix: basal pattern naming option crash
fix: exception catches added for odd errors reported in crashlytics
fix: urchin last bolus value when >20 units displayed incorrectly
add: nightscout alarm notifications for calibration '?NC' and expired sensor '?SN' to use with Pushover / IFTTT
add: option to change Grams Per Exchange value from fixed default 15g (pump hard coded value) to a range of 5g to 20g
add: option to use old method for requesting usb permission from the app (default is via the OS)
add: messaging for busy states
changed limiter sizes for upload processing per poll period to reduce initial nightscout server stress