Easily add a new rules with snapshot

CLI with no version
```
$ solidarity snapshot cli detox
Would you like to add the binary `detox` to your Solidarity file? (Y/n) True
Update complete
```

CLI with a version
```shell
$ solidarity snapshot cli node
Would you like to add the binary `node` to your Solidarity file? (Y/n) True
Would you like to enforce a version requirement? (Y/n) True
Your system currently has version 8.6.0
Semver requirement for `node` binary : ^8.6.0
Update complete
```

ENV var
```
$ solidarity snapshot env PATH
Would you like to add the environment requirement `PATH` to you Solidarity file? (Y/n) True
Update complete
```

File/Dir also.
```
$ solidarity snapshot file ./nachos
Would you like to add the file requirement `./nachos` to you Solidarity file? (Y/n) True
Update complete
```

Start at the snapshot CLI command and trace how cli, env, file, and directory requirements are represented and written to the Solidarity file. Compare the command’s behavior with the examples; done means each type prompts appropriately, applies the optional version requirement for binaries, and reports Update complete.

Written by the indexing model from the issue text.