Set version number back to 1.0-SNAPSHOT
Minor logging refactoring to LTI result return

I've slightly refactored this so that I can log the response message
body before determining whether the process was successful or not.
This might help with debugging certain TCs
Minor typo fix
Minor fixes to LtiOutcomeService while debugging:

* Added XML escaping for lis_result_sourcedid, as this is often not an
identifier like the spec suggests. (Hello Moodle!)
* Fixed an incomplete log message added in previous commit.
Further improvements to LtiOutcomeService:

* LIS result sending method is now independent of the rest of the
QTIWorks Engine machinery, so can be invoked easily if debugging of
TCs is necessary.
* HTTP request now includes Content-Type and Content-Length headers
Further minor refactor of LTI/OAuth stuff

I've moved most of the key stuff into a single utility class
to make it easier to test/debug things.
Fix for issue #37

I've added Spring's CharacterEncodingFilter to set the encoding
of incoming data to UTF-8 if it hasn't been supplied by the browser,
which fixes this. Also set accept-charset="UTF-8" on the candidate
forms too for consistency.
Fixed MVC routing target when deleting deliveries

This was still pointing to the old "list deliveries" action,
which was absorbed into the "show assessment" action. Now fixed.
Delivery deletion now removes LTI link candidates

Recall that LTI link candidates are created especially for a delivery.
We now delete all of these users when a delivery is deleted, which is
the correct thing to do with regards to privacy and data protection.
(The original behavious was to keep the candidates in the DB, which
was an oversight.)
LIS result handling is now NS agnostic

Moodle is sending back its imsx_POXEnvelopeResponse in a different
namespace to the one stated in the LTI spec. As such, I think it's
safer just to accept any NS and just check the localNames.
Excluded commons-logging dep from httpclient
Minor tweak to servlet config

* Used newest version of servlet 2.5 NS
* Added metadata-complete attribute
Renamed stylesheetCache -> xsltStylesheetCache
Cosmetic spacing fix
QWDepException now extends QWRuntimeException
Change to ThreadLocal usage in IdentityService

Entries are now removed from the ThreadLocal when being
set to null, rather than left as nulls.
Added ThreadLocalCleaner memory leak helper

This bean searches all ThreadLocals and purges any values associated
with the application and its dependencies. This should reduce
memory leakage when the webapp gets restarted.
Added better tracking of OAuth nonces

These are now recorded in the persistence model via a new LtiNonce entity.
A new LtiOAuthValidationService class handles the validation and
timestamp/nonce checking of LTI requests. The ScheduledService
now calls a maintenance method to delete old nonces.
Replaced remaining commons-lang uses with guava
Minor local/param variable renaming for clarity