ENH: Update qRestAPI (Adds Qt5 support, Fix misc issues)

$ git shortlog 5a81c92..9d3cfb6 --no-merges
Andreas Fetzer (16):
Added support for sending HEAD request
Moved deletion of qRestResult outside the if/else in order to prevent leakage.
head request is now asynchronous.
Removed unused parameter, adapted documentation
Started to fix file upload
Remove duplicate connections. These ones are already created in the upload and download functions
Refactored upload function analogous to download
Removed unused slot
Emitting signal if upload is finished
Removed debug message
Pass rawheaders again
Added proper error handling in case the file could not be read. Also deleted input in case of an error.
Set parent for QFile in case of upload or download is called to assure that the file is always deleted.
Removed unnecessary uploadFinished signal
Added possibility to set a http network proxy
Use correct indent

Jean-Christophe Fillion-Robin (1):
Fix unused variable warnings

Miklos Espak (4):
Exporting qRestAPI_LIBRARY_DIRS for use by client code
No data is not regarded as error in XNAT queries
XNAT specific code removed
Return 0 if result has already been taken

Sascha Zelzer (16):
Added error reporting to qRestAPI.
Don't take result object before calling waitForDone().
Fixed inverted logic for returning true on success.
Clean-up query results.
Added error code for authentication errors.
Fixed wrong error code assignment.
Properly convert Qt network error codes to string.
Only parse the response if no network error occurred.
Added raw headers from the http response to qRestResult.
Create result objects based on a string id using the Qt meta type system.
Removed the "result" methods which instantiate objects.
Removed template method declarations for already removed implementations.
Deleting the QNetworkManager instance too early may lead to crashes.
Restore Qt 4.6.2 compatibility.
Added Qt5 compatibility.
The Result map can be empty on connection errors. Check that.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25840 3bd1e089-480b-0410-8dfb-8563597acbee