watcher: Refactor ConnectionManager config

[yourbuddyconner]

Right now the connectionManagers config in the watcher-partial.json looks like this:

"connectionManagers": [
    {
      "address": "0x0000000000000000000000000000000000000000",
      "domain": "60",
      "name": "ethereum",
      "rpcStyle": "ethereum",
      "config": {
        "connection": {
          "type": "ws",
          "url": "ws://localhost:8545"
        }
      }
    },
    {
      "address": "0x0000000000000000000000000000000000000000",
      "domain": "61",
      "name": "eth-classic",
      "rpcStyle": "ethereum",
      "config": {
        "connection": {
          "type": "ws",
          "url": "ws://localhost:8545"
        }
      }
    }
  ]

This is problematic because it's not possible to set sub-keys of these configs via Environment Variable. As such we need to refactor this config to be a map, probably something like this:

"connectionManagers": {
    "BridgeRouter": {
      "address": "0x0000000000000000000000000000000000000000",
      "network": "kovan",
      "name": "BridgeRouter"
    },
    "BridgeRouter": {
      "address": "0x0000000000000000000000000000000000000000",
      "network": "rinkeby",
      "name": "BridgeRouter"
    },
    "BridgeRouter": {
      "address": "0x0000000000000000000000000000000000000000",
      "network": "rinkeby",
      "name": "BridgeRouter"
    }
  }