updated initialize() to take an input file or revert to default
updated initialize() to take an input file or revert to default

cmshobe/landlab,Carralex/landlab,RondaStrauch/landlab,landlab/landlab,SiccarPoint/landlab,amandersillinois/landlab,amandersillinois/landlab,decvalts/landlab,laijingtao/landlab,Carralex/landlab,csherwood-usgs/landlab,landlab/landlab,cmshobe/landlab,Carralex/landlab,ManuSchmi88/landlab,ManuSchmi88/landlab,RondaStrauch/landlab,ManuSchmi88/landlab,RondaStrauch/landlab,SiccarPoint/landlab,cmshobe/landlab,decvalts/landlab,csherwood-usgs/landlab,laijingtao/landlab,landlab/landlab