Fix this.pos initialisation
Introduce field level metadata.

Changes include:
 * Added Metadata (immutable) and MetadataBuilder to API. Opted to make these concrete objects (which the other builders are in fact not).
 * Record extended with metadata get/set methods
 * read/write path support for metadata
    * for fields without metadata, storage format stays the same
    * 3 bits of the prefix-byte are used to indicate the metadata serialization version and at the same time the prescence of metadata (000 = no metadata). See new class FieldFlags were it's documented.
    * metadata not supported for versioned-mutable fields (matter of saving implementation time on something that probably has little value)
    * read always decodes the metadata (if this would be a problem, we can make loading metadata optional and/or do the decoding lazily)
 * Added metadata to binary record serialization which goes over avro (bumped serialization version number)
Merge branch 'master' into fieldmetadata
Merge branch 'master' into fieldmetadata
FieldValueFltr support metadata + drop hbase-ext

Let FieldValueFilter also work for fields that have metadata (for which the cell format is different). This involves adding a custom HBase filter.

Moved hbase-ext code in with repository-impl. This wasn't very necessary right now (just reusing FieldFlags class), but will be necessary anyway once we have filters supporting metadata.

Impact is that hadoop-test-fw cannot have a dependency on hbase-ext, now repository-impl, anymore since this would result in circular dependencies. Decided to solve this by making a separate project, hadoop-test-fw-standalone, that does have dependencies on the things that Lily requires to be on the regionserver classpath (and removed these deps from hadoop-test-fw, which is not an issue for embed-mode since the stuff that needs to be on the classpath is usually also a maven dependency).

The launch-hadoop script is now in global/hadoop-test-fw-standalone/target
Implement json ser/deser of field metadata
Support metadata in record builder
No metadata on blob fields, enforce this

Metadata on blob fields is not (yet) supported as it would likely require work on the "ContainsValueComparator".
Support metadata printing in PrintUtil

this makes that metadata shows up in the output of lily-scan-records.
Small metadata fixes.

Specifically:
 - make sure no empty metadata (0 fields) is stored
 - fix in comparing old & new metadata when using non-string values
delete-flag/marker cleanup

- split delete marker use of type mgr & repo (in repo, it is generalized to 'field flags', as it now includes info on metadata precense/version)
- in repo, use FieldFlags class everywhere instead of delete marker constants
- cleanup/simplify FieldFlags class
Merge branch 'master' into fieldmetadata