IsAlive API endpoint

[GET] /api/isalive

Should return some general service info. Used to check if the service is running. Response:

```js
{
// Name of the service
“name”: “string”,
// Version of the service
“version”: “string”,
// ENV_INFO environment variable value
“env”: “string”,
// Flag, which indicates if the service is built
// in the debug configuration or not
“isDebug”: boolean
}
```

Python implementation

```py
@api.route('/isalive', methods=['GET'])
def isalive():
"""
Return some general service info. Used to check if service is running
"""

version = get_version()

if "error" in version:
return make_response(
jsonify(build_error(version["error"])),
version["status"]
)

result = {
"name": app.config['SKYCOIN_FIBER_NAME'],
"version": version,
"env": app.config["ENVIRONMENT"],
"isDebug": app.config["DEBUG"],
"contractVersion": app.config['SWAGGER_API_VERSION']
}

return jsonify(result)
```