secondary_ranges does not support subnets with the same name

[jhulndev]

Since secondary_ranges is a map, it is not possible to utilize it if your subnets have the same name. In GCP the subnet names must be unique for a given region, this module should allow for the same.

[morgante]

I think we will fix this in #86.

[jhulndev]

It looks like #69 could actually fix this as well.

[imrannayer]

@jason-huling is it still an issue or should we close this?