fix favicon, convert white to alpha
fix favicon, convert white to alpha

Sage-Bionetworks/SynapseWebClient,Sage-Bionetworks/SynapseWebClient,jay-hodgson/SynapseWebClient,jay-hodgson/SynapseWebClient,jay-hodgson/SynapseWebClient,jay-hodgson/SynapseWebClient,Sage-Bionetworks/SynapseWebClient,Sage-Bionetworks/SynapseWebClient