INT-3368: `SyslogToMapTrans`: Make `TAG` Optional

JIRA: https://jira.spring.io/browse/INT-3368

INT-3368: PR comments
Reduce MBF Warning Logs to DEBUG

When the bean factory is not provided a WARN log was issued
because the message builder factory cannot be found.

Reduce the logs to DEBUG.
Use JDK8 on Travis

This will catch any Javadoc violations in pull requests.

No need for an explicit `api` task; it's invoked in the standard
travis `assemble` step.
INT-3101 Allow PPC for 'durable' in GF CQ Adapter

JIRA: https://jira.spring.io/browse/INT-3101

Change schema type from xsd:boolean to union with string and boolean.
INT-2738 Add Missing `getComponentType()` Methods

JIRA: https://jira.spring.io/browse/INT-2738

Add a `getComponentType()` method for all handlers,
message producers, and message sources that implement
`NamedComponent` (see `SPCA.getComponentType()`).

Add rome as an optional dependency - STS complained
because AtomFeedHttpMessageConverter has a dependency
on it.
INT-3338: MongoMS: Add `priority` and `sequence`

JIRA: https://jira.spring.io/browse/INT-3338

INT-3338: Add Docs

INT-3338: Make `priority` 'smart'

Add `Sort` for all group queries dependently of `priorityEnabled`.
Avoids the need to configure separate collections for different type of `MessageStore`

INT-3338: Add `MongoDbChannelMessageStore`

INT-3338: Polishing, Fixes, Improvements

Doc Polishing

Fix stream test.
INT-3367: Add `GemfireMetadataStore`

JIRA: https://jira.spring.io/browse/INT-3367