Update CHANGELOG for v0.5
Update CHANGELOG for v0.5

tempbottle/pycapnp,rcrowder/pycapnp,SymbiFlow/pycapnp,SymbiFlow/pycapnp,jparyani/pycapnp,rcrowder/pycapnp,rcrowder/pycapnp,jparyani/pycapnp,SymbiFlow/pycapnp,SymbiFlow/pycapnp,jparyani/pycapnp,jparyani/pycapnp,tempbottle/pycapnp,tempbottle/pycapnp,tempbottle/pycapnp,rcrowder/pycapnp