Cleanup node_info Endpoint

[alexanderbez]

• Remove some redundant code and endpoints
• Update node_info endpoint to also include application version info

new output:

{
    "application_version": {
        "build_tags": "netgo,ledger",
        "client_name": "gaiacli",
        "commit": "c1ae72295c72ce548f271c8c337aeb662a48b5a2",
        "go": "go version go1.12.5 darwin/amd64",
        "name": "gaia",
        "server_name": "gaiad",
        "version": "0.0.0-43-gc1ae722"
    },
    "node_info": {
        "channels": "4020212223303800",
        "id": "55b46a2f3f5cb1d9e8d092c5c4cdb21d158553c9",
        "listen_addr": "tcp://0.0.0.0:26656",
        "moniker": "node0",
        "network": "chain-16yZ57",
        "other": {
            "rpc_address": "tcp://0.0.0.0:26657",
            "tx_index": "on"
        },
        "protocol_version": {
            "app": "0",
            "block": "10",
            "p2p": "7"
        },
        "version": "0.32.1"
    }
}

---

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry: clog add [section] [-t <tag>] [-m <msg>]

• Re-reviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #4837 into master will decrease coverage by 0.04%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #4837      +/-   ##
==========================================
- Coverage   54.18%   54.14%   -0.05%     
==========================================
  Files         269      269              
  Lines       17191    17209      +18     
==========================================
+ Hits         9315     9317       +2     
- Misses       7186     7202      +16     
  Partials      690      690