[app/explorer-v2][s]: improve documentation of Explorer js object plus minor improvement so we don't error if no aggregator attribute on config passed to explorer.
[app/explorer-v2][s]: improve documentation of Explorer js object plus minor improvement so we don't error if no aggregator attribute on config passed to explorer.

RCGTDev/openspendingjs,openspending/openspendingjs-old,openspending/openspendingjs-old,openspending/openspendingjs,openspending/openspendingjs,RCGTDev/openspendingjs,openspending/openspendingjs-old,openspending/openspendingjs,openspending/openspendingjs,RCGTDev/openspendingjs,RCGTDev/openspendingjs,openspending/openspendingjs-old