fix querystring converter with empty input

(also pin plone.app.robotframework since release 0.7.6 doesn't work with the other robotframework pins from Plone 4.3)
Merge pull request #54 from plone/296-querystring

fix querystring converter with empty input
Merge pull request #53 from plone/amleczko-add_richtext_widget

add richtext field/widget support and remove Products.TinyMCE dependency
Travis build 1274 pushed 'widgets' bundle resources.
Travis build 1276 pushed 'widgets' bundle resources.
Fix RichTextWidget tests for Plone 4.3.
Travis build 1283 pushed 'widgets' bundle resources.
Merge pull request #55 from plone/fix-richtextwidget-tests

Fix RichTextWidget tests for Plone 4.3.
Create robot tests for querystring widget
'pattern_options' should be there
Merge pull request #52 from plone/ale-rt-test_querystring_widget

Test querystring widget
add some more tests for richtext widget
Merge pull request #56 from plone/amleczko-thursday-1

add more tests for richtext widget
make tests work in p5
Merge pull request #57 from plone/davisagli-fix-test

fix date widget test in p5
Travis build 1314 pushed 'widgets' bundle resources.
Travis build 1316 pushed 'widgets' bundle resources.
Pin plone.app.robotframework = 0.8.2 to for 'Debug'-keyword
Travis build 1320 pushed 'widgets' bundle resources.
Add testing layer for testing SelectWidget