SGF-347 - Updated changelog.
SGF-355 - Updated changelog.
SGF-355 - Prepare 1.6.0.M1 (Fowler M1).

Minor dependency upgrades.
SGF-355 - Release version 1.6.0.M1.
SGF- 355 - Prepare next development iteration.
SGF-355 - After release cleanups.
SGF-289 - Enumeration restrictions (xsd:enumeration) should be avoided in the XML schema.

Removed the XSD enumeration restriction on the 'index-update-type' attribute of the 'baseRegionType' element in the Spring GemFire XML Schema (XSD).
SGF-289 - Enumeration restrictions (xsd:enumeration) should be avoided in the XML schema.

Removed the XSD enumeration restriction on the 'action' attribute of the 'expirationType' XSD complex-type definition used by the 'region-ttl', 'region-tti', 'entry-ttl', and 'entry-tti' elements in the 'baseReadOnlyRegionType' inside the Spring GemFire XML Schema (XSD).