Fix error when editing OAuth app registration and only changing the icon.
Fix error when editing OAuth app registration and only changing the icon.

gnusocial/mainline,foocorp/gnu-social,sikevux/bsk-social,d3vgru/StatusNet,furtherfield/gnu-social,Piratas/tortuga,eXcomm/gnu-social,zcopley/zcopleys-statusnet-clone,zh/statusnet,faulteh/gnu-social,UngPirat/freesocial,charnimda/lgbtpzn-social,furtherfield/gnu-social,gnusocial/mainline,znarf/statusnet-ladistribution,chimo/social,charlycoste/StatusNet,xebia/statusnet-oauth2,faulteh/gnu-social,faulteh/gnu-social,minmb/statusnet,xebia/statusnet-oauth2,shashi/StatusNet,zh/statusnet,brion/StatusNet,Piratas/tortuga,UngPirat/freesocial,znarf/statusnet-ladistribution,charlycoste/StatusNet,Piratas/tortuga,faulteh/gnu-social,zcopley/StatusNet,shashi/StatusNet,chimo/social,zcopley/StatusNet,furtherfield/gnu-social,chimo/social,foocorp/gnu-social,bankonme/gnu-social,xebia/statusnet-oauth2,eXcomm/gnu-social,charnimda/lgbtpzn-social,brion/StatusNet,UngPirat/freesocial,zcopley/zcopleys-statusnet-clone,studio666/gnu-social,sikevux/bsk-social,shashi/StatusNet,foocorp/gnu-social,d3vgru/StatusNet,Piratas/tortuga,zcopley/StatusNet,zcopley/zcopleys-statusnet-clone,bankonme/gnu-social,zh/statusnet,csarven/statusnet,d3vgru/StatusNet,brion/StatusNet,csarven/statusnet,studio666/gnu-social,gnusocial/mainline,bankonme/gnu-social,minmb/statusnet,csarven/statusnet,bankonme/gnu-social,sikevux/bsk-social,sikevux/bsk-social,minmb/statusnet,csarven/statusnet,gnusocial/mainline,studio666/gnu-social,charnimda/lgbtpzn-social,charlycoste/StatusNet,znarf/statusnet-ladistribution,furtherfield/gnu-social,studio666/gnu-social,eXcomm/gnu-social,eXcomm/gnu-social