MODE-2254 Changed the JsonSidecarExtraPropertiesStore to avoid trying to interpret string properties as dates by default and also fixed a potential StringIndexOutOfBounds exception when converting ISO 8601 strings to dates.

Conflicts:
	modeshape-jcr/src/test/java/org/modeshape/connector/filesystem/FileSystemConnectorTest.java
Merge pull request #1176 from hchiorean/MODE-2254

MODE-2254 Changed the JsonSidecarExtraPropertiesStore to avoid trying to interpret string properties as dates by default