models: Rename realm emoji to custom emoji.
models: Rename realm emoji to custom emoji.

punchagan/zulip,jackrzhang/zulip,tommyip/zulip,brainwane/zulip,showell/zulip,timabbott/zulip,zulip/zulip,zulip/zulip,zulip/zulip,tommyip/zulip,shubhamdhama/zulip,kou/zulip,dhcrzf/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,showell/zulip,timabbott/zulip,zulip/zulip,kou/zulip,synicalsyntax/zulip,showell/zulip,tommyip/zulip,brainwane/zulip,andersk/zulip,jackrzhang/zulip,tommyip/zulip,dhcrzf/zulip,showell/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,hackerkid/zulip,timabbott/zulip,punchagan/zulip,synicalsyntax/zulip,zulip/zulip,rht/zulip,brainwane/zulip,hackerkid/zulip,brainwane/zulip,jackrzhang/zulip,shubhamdhama/zulip,dhcrzf/zulip,jackrzhang/zulip,rishig/zulip,timabbott/zulip,synicalsyntax/zulip,kou/zulip,andersk/zulip,andersk/zulip,dhcrzf/zulip,andersk/zulip,shubhamdhama/zulip,kou/zulip,zulip/zulip,jackrzhang/zulip,showell/zulip,rht/zulip,rishig/zulip,tommyip/zulip,rht/zulip,eeshangarg/zulip,synicalsyntax/zulip,dhcrzf/zulip,jackrzhang/zulip,zulip/zulip,shubhamdhama/zulip,rishig/zulip,shubhamdhama/zulip,hackerkid/zulip,brainwane/zulip,punchagan/zulip,hackerkid/zulip,shubhamdhama/zulip,tommyip/zulip,kou/zulip,timabbott/zulip,kou/zulip,brainwane/zulip,eeshangarg/zulip,jackrzhang/zulip,hackerkid/zulip,synicalsyntax/zulip,showell/zulip,eeshangarg/zulip,kou/zulip,punchagan/zulip,andersk/zulip,rishig/zulip,rishig/zulip,rht/zulip,punchagan/zulip,rishig/zulip,dhcrzf/zulip,timabbott/zulip,timabbott/zulip,showell/zulip,hackerkid/zulip,synicalsyntax/zulip,shubhamdhama/zulip,rht/zulip,brainwane/zulip,andersk/zulip,synicalsyntax/zulip,dhcrzf/zulip,eeshangarg/zulip,tommyip/zulip,rishig/zulip,punchagan/zulip,rht/zulip,eeshangarg/zulip