Reducing binder invoking when scrolling

Drawing frame is delay due to losts of binder invoking from
getAccountIcon. When fetching the account icon, need call
getAccountOrNull every time that invokes two remote methods
such as getDefaultDialerPackage and getCallCapablePhoneAccounts.

Put the drawable of the icon into cache so that reduces invoking
getAccountOrNull, otherwise avoid to call the remote method
isVoiceMailNumber.

Change-Id: Ib03975cc6586980189a10f2992df445a26add18b
CRs-Fixed: 1033851