codegen not escaping swift keywords

[Rolandas Razma]

this is same as #37

[Rolandas Razma]

quick workaround for me was to add

perl -i -0pe 's/case (self|do|as|is) =/case `$1` =/gms' Graphaello.swift

after

graphaello codegen --project $PROJECT_FILE_PATH --apollo derivedData