[GIP-1] Setting a conversion rate for SPIN to GYFI and GYFI claim options

## TL;DR * We propose to set the SPIN-to-GYFI conversion rate at 1066 SPIN per GYFI. We propose that SPIN holders can boost their conversion rate by up to 150% by choosing to lock up their tokens. * Currently, around 300m SPIN are allocated. At the above proposed conversion rates, this corresponds to 2.05% – 5.14% of GYFI total supply allocated to SPIN holders (where the range depends on the lockup option chosen by users). * We propose to increase the cap on SPIN from 500m to 700m. If all...