Add check for certain elements that the correct children exist.

For elements that can have children or nilReason attributes it is possible to have the element defined but no children and the xsd validation passes even though the metadata should not be considered valid.

For example gmd:citation can either have nilReason or CI_Citation as a child.  However no errors are raised if the gmd:citation element is present but has no children or a nilReason attribute.  This commit adds checks for some of these cases.
Added some missing strings
add check for DateTime as suggested by fxp.
Merge pull request #428 from jesseeichar/isoMissingChildren

Add check for certain elements that the correct children exist.

Reviewed by FXP
Add capability to override a label for a field defined by xpath.
Merge remote-tracking branch 'origin/develop' into develop
Widgets / Metadata privileges / Avoid JS error on some configuration.
Fixes for correct URLs on windows and linux - some fixes are similar to
those proposed by fxp in #135 and this patch fixes problems described in #218
Requires patched xml-resolver jar from commit
0e5b1af75f05a00d02bb6c85dbbc573aec7395ff which is a fix for issue #339

Conflicts:
	jeeves/pom.xml
	jeeves/src/main/java/jeeves/utils/Xml.java
	jeeves/src/main/java/jeeves/utils/XmlResolver.java
	web/src/main/java/org/fao/geonet/kernel/SchemaManager.java
Use eclipse URIUtils to avoid java7 dependency

Conflicts:
	jeeves/src/main/java/jeeves/utils/Xml.java
Improve layout for duration field on small screen.
Improve schema for editor configuration.
Add indeterminate position for temporal extent in INSPIRE view. Avoid to loose info in contact template field when switching to INSPIRE view.
Add blank option for codelist.
Pluralize label.
Restore XSD validation report translation of error messages.
Avoid empty attribute indeterminate position.
Merge remote-tracking branch 'upstream/develop' into develop