Change to ZIP/XML import logic

Fixes bug #28. We no longer check the MIME type of ZIP content
and instead try to expand it and succeed if a valid ZIP entry is
found. Some changes have been made to the API to accommodate this
safely.
Ready for 1.0-M4a.

(This cherry-picks commit 99b5db5 from the master branch, which
rewrote the CP-handling code to make it less fussy.)
Cherry-picked new MathJax URL from master branch
Patch release (1.0-M4b) to use new MathJax SSL CDN

(The old SSN CDN has gone offline, so I've cherry-picked the
new URL and the upgrade to MathJax 2.1 from the master branch.)
Merge remote branch 'origin/production' into production

This is after merging the master branch into production, then
sorting out the divergence due to the 2 interim releases made after
M4 was released. Nothing exciting happens here!

Conflicts:
	pom.xml
	qtiworks-code-examples/pom.xml
	qtiworks-engine-manager/pom.xml
	qtiworks-engine/pom.xml
	qtiworks-engine/src/main/java/uk/ac/ed/ph/qtiworks/services/AssessmentManagementService.java
	qtiworks-engine/src/main/java/uk/ac/ed/ph/qtiworks/services/AssessmentPackageFileImporter.java
	qtiworks-engine/src/main/java/uk/ac/ed/ph/qtiworks/services/StandaloneValidationService.java
	qtiworks-engine/src/main/java/uk/ac/ed/ph/qtiworks/services/base/ServiceUtilities.java
	qtiworks-engine/src/main/java/uk/ac/ed/ph/qtiworks/utils/IoUtilities.java
	qtiworks-engine/src/main/resources/rendering-xslt/serialize.xsl
	qtiworks-engine/src/test/java/uk/ac/ed/ph/qtiworks/services/AssessmentPackageFileImporterTest.java
	qtiworks-engine/src/test/java/uk/ac/ed/ph/qtiworks/testutils/ClassPathMultipartFile.java
	qtiworks-jqtiplus/pom.xml
	qtiworks-mathassess-glue/pom.xml
	qtiworks-mathassess/pom.xml
	qtiworks-samples/pom.xml
Ready for 1.0-beta1
Changed remaining www2.ph -> webapps.ph URLs
Removed commented out-of-date code.

(This became redundant due to late changes in the spec.)
Some general gardening on JQTI+:

* Removed commented-out code
* Pruned more landfill JavaDoc
* Improved some doc comments

No functional changes here.
Merged ContainerBlock into ForeignElement
Completed interface impls for InfoControl
JQTI+: added stylesheet assn rubricBlock

This was a late addition to the spec. Note that QTIWorks Engine's
renderingcurrently does nothing useful with this - it's non-trivial to
implement.
Further tidying to JQTI+:

* Deprecated getChildren() methods for navigating the QTI class
hierarchy so that they consistently use names based on the content
class that will be returend.
* Some minor fixes to interface impls of content classes
* Further minor JavaDoc improvements.