test(rxForm): Dropdown page object

```
10:05:20 {e2e-rx-form-generic-helpers-form-fill} ~/code/js/encore-ui
$: ./node_modules/protractor/bin/protractor protractor.conf.js --specs=src/rxForm/docs/rxForm.midway.js 
Using the selenium server at http://localhost:4444/wd/hub


  rxForm
    form filling
      ✓ should have filled the plainTextbox value 
      ✓ should have unchecked the requireName checkbox 
      ✓ should have selected the volume type 
    dropdown
      ✓ should have the right number of options 
      1) should have every option listed
      ✓ should have a selected option by default 
      ✓ should not report a different option as selected 
      ✓ should report non-existing options 
      ✓ should report existing options 
      ✓ should select a new option 
      ✓ should have a value 


  10 passing (9s)
  1 failing

  1) rxForm dropdown should have every option listed:

      AssertionError: expected [ Array(11) ] to deeply equal [ Array(11) ]
      + expected - actual

       [
      +  "SATAAAA",
      -  "SATA",
         "SSD",
         "CD",
         "DVD",
         "BLURAY",
```