echo 1.573.0

feat(core): Front50 graphql client (#357)

An experimental front50/graphql integration. The schema
exposed by front50 only really supports pipelines with
cron triggers. Similarly, we haven't implemented a query
builder or anything of that sort on the Echo side.

Should we see positive results from this integration,
a more focused effort will be put in to offer a more
fully featured integration.

Usage:

```java
GraphQLQueryResponse resp = front50.query(GraphQLQuery.pipelines("cron"));
```