Allow spaces in element name in "Configure Element with Command Line Tool" dialog

Scenario:

1. Open the "Workflow Designer".
2. Click the "Create element with command line tool" button on the toolbar.
3. Select the "Name" field and try to enter a string with spaces.
   Current result: spaces are not allowed. Some other valid characters are not allowed as well.

There are some rules for element names. They are not so strict as you can see in the "Configure Element with Command Line Tool" dialog. Make the name validator respect common elements naming rules.