Junit outputter

[rerpha]

I have added the ability to output to a junit-style xml file with the results of the test. not sure what to do for build errors just yet but they shouldn't get used anyway so the xml file shows test successes and failures.

[rerpha]

here is some example xml i generated with the flag:

<testsuites>
    <testsuite name="features" tests="8">
        <testcase classname="NXtomo" name="1">
            <failure type="AssertionError">No NXtomo entries in this entry</failure>
        </testcase>
        <testcase classname="NXdetector with image key" name="2">
            <failure type="AssertionError">This file does not contain an NXdetector with the image_key field</failure>
        </testcase>
        <testcase classname="GDA scan command" name="3">
            <failure type="AssertionError">There is no GDA scan command in this file.</failure>
        </testcase>
        <testcase classname="NXdiffraction" name="7">
            <failure type="AssertionError">No NXdiffraction entries found</failure>
        </testcase>
        <testcase classname="Has title" name="4120907338832439328">
            <failure type="AssertionError">This file does not contain a title field</failure>
        </testcase>
        <testcase classname="Has experiment_identifier" name="9800137637449172744">
            <failure type="AssertionError">This file does not contain an experiment_identfier field</failure>
        </testcase>
        <testcase classname="NXData with Cansas NeXus Axis" name="15105073150200643585">
            <failure type="AssertionError">No NXdata with cansas Axis found
</failure>
        </testcase>
        <testcase classname="NXcitation information" name="15105073150200643586">
            <failure type="AssertionError">This file does not contain any NXcite information</failure>
        </testcase>
    </testsuite>
</testsuites>

[rerpha]

refs #1