Replace Assertion that renewable resources exist in model regions, with checks + bypasses in build_renewable_profiles

[ktehranchi]

          This caused the following error to appear when running the default configuration file. I had to remove the `offwind` and `offwind_floating` techs to get it to work. If this is required, we should probably just remove them from the default config, or (ideally?) 

Originally posted by @trevorb1 in #420 (comment)

Trevor identified that we should ideally bypass a renewable resource rather than requiring the user to update the configuration file. This is for cases where a user is building a model of (example: Colorado, where Offshore Wind isn't eligible)