First pass at changing the viewport selector to drop-down.

Change-Id: I33e2106ae4a17a9ea9912c93f0ad79f6c2534f3a
Remove image button.

Change-Id: Ieca5c5d6b26cd7d7ffd778e67bd79950762df1e6
Integrated an object-oriented, phased approach to web testing.

With the integration of testing base classes written by Roni
Choudhury, we needed to refactor the existing web-based testing
scripts.  The introduction of these new base classes allows us
to support multiple baseline images and testing in different
browsers seamlessly.

Now, new test scripts should extend one of the three new testing
base classes: WebTest, BrowserBasedWebTest, or
ImageComparatorWebTest, and override some or all of the testing
phase methods implemented in those classes.  New tests can be
given any class name, and the class will be instantiated
dynamically at run-time by the newly refactored vtk.web.testing
module.

Also changed was the FindSeleniumDrivers cmake script, so that
at least the firefox webdriver extension can be found.  More
changes were required in the ParaViewTestingMacros cmake file,
where I fixed a bug that kept any but the first browsers tests
from being registered, and where I added a new argument to the
addition of test scritps: --test-use-browser.

Change-Id: Ie405280d2efefe13e0f09d7562ad15c7017a3628
Fixed test names, fixed broken element selection, viewport resize.

Test names now follow standard convention of prefix.testname.  Also
fixed a problem with the web visualizer can test where some element
name had changed in application and test could no longer find it.
Also now resize viewport explicitly in web tests so that different
broswers do not get different image sizes.

Change-Id: Icd1b27b5066875247e95054672116da9052e14af
Disable pvweb tests if the Python version is not at least 2.7

Change-Id: I7802b7077626231ee888ed776ec095342cf79482
Extend visualizer arguments with file grouping and filtering regex

Change-Id: I3e13b9809076d99f10f0c85357b8ac5fef51913f
Move VTK forward to have new session manager url

Change-Id: Iec60d8fab9ad2c0e47494869819a887ae0d87238
Update VTK to origin/master

Change-Id: I54651cd8747660722cb19ede673ce7376cd7d86c
Merge topic 'pvweb-group-pattern-option'

90e56d4 Extend visualizer arguments with file grouping and filtering regex
Merge topic 'pvweb-integrate-test-packages-alternate'

8068e91 Disable pvweb tests if the Python version is not at least 2.7
b280128 Fixed test names, fixed broken element selection, viewport resize.
5141f40 Integrated an object-oriented, phased approach to web testing.
Merge topic 'pvweb-session-manager-url-update'

b7b534c Move VTK forward to have new session manager url
Merge topic 'pvwev-select-box-for-viewport-selection'

e7c04ef Remove image button.
05d7e09 First pass at changing the viewport selector to drop-down.
Merge topic 'update_vtk_master'

2f40ef6 Update VTK to origin/master