Add methods for dealing with signatures to File model
Add methods for dealing with signatures to File model

pypa/warehouse,chopmann/warehouse,dstufft/warehouse,karan/warehouse,alex/warehouse,HonzaKral/warehouse,HonzaKral/warehouse,pypa/warehouse,wlonk/warehouse,ismail-s/warehouse,karan/warehouse,dstufft/warehouse,wlonk/warehouse,chopmann/warehouse,dstufft/warehouse,pypa/warehouse,pypa/warehouse,ismail-s/warehouse,ismail-s/warehouse,alex/warehouse,alex/warehouse,ismail-s/warehouse,dstufft/warehouse,chopmann/warehouse,karan/warehouse,alex/warehouse,HonzaKral/warehouse,karan/warehouse,wlonk/warehouse,HonzaKral/warehouse,ismail-s/warehouse,karan/warehouse,alex/warehouse