Add empty sync status view controller.
Add ignore sync errors settings flag.
Implement sync status indicator. Closes #179.
Set HTTP timeout to 10s.
Merge pull request #289 from toggl/roosmaa-sync-status

Implement sync status bar for iOS.

Conflicts:
	Ross/Data/SettingsStore.cs
	Ross/Resources/en.lproj/Localizable.strings
	Ross/Ross.csproj