Update Rust and Types

[ethanfrey]

Closes #196

• Update CI and Docker builds to Rust 1.50
• Build and publish new docker build containers
• Update Go types
• Update test contracts to v0.14.0-alpha1

[webmaster128]

Looks good. I just don't know about the JSON representation of pub gas_limit: Option<u64>

[webmaster128]

The JSON schema says this is null or an integer:

    "SubMsg_for_CustomMsg": {
      "description": "A sub-message that will guarantee a subcall_response callback on success or error Note on error the subcall will revert any partial state changes due to this message, but not revert any state changes in the calling contract (that must be done in the subcall_response entry point)",
      "type": "object",
      "required": [
        "id",
        "msg"
      ],
      "properties": {
        "gas_limit": {
          "type": [
            "integer",
            "null"
          ],
          "format": "uint64",
          "minimum": 0.0
        },
        "id": {
          "type": "integer",
          "format": "uint64",
          "minimum": 0.0
        },
        "msg": {
          "$ref": "#/definitions/CosmosMsg_for_CustomMsg"
        }
      }
    },

Are you sure it works with *uint64 and omitempty?

[ethanfrey]

It is not a required field. This works fine

[webmaster128]

Alright, and it only needs to work from Rust to Go. Then we receive a number of null in Go.