DropdownItems have bad id, cause console warnings

[jeff-phillips-18]

Using DropdownItems creates items with duplicate invalid id settings causing warnings in the console:

t-s:1 [DOM] Found 7 elements with non-unique id #: (More info: https://goo.gl/9p2vKq) 
<button tabindex=​"-1" type=​"button" class=​"pf-c-dropdown__menu-item" id>​…​
<button tabindex=​"-1" type=​"button" class=​"pf-c-dropdown__menu-item" id>​…
<button tabindex=​"-1" type=​"button" class=​"pf-c-dropdown__menu-item" id>​…
<button tabindex=​"-1" type=​"button" class=​"pf-c-dropdown__menu-item" id>​…
<button tabindex=​"-1" type=​"button" class=​"pf-c-dropdown__menu-item" id>​…
<button tabindex=​"-1" type=​"button" class=​"pf-c-dropdown__menu-item" id>​…
<button tabindex=​"-1" type=​"button" class=​"pf-c-dropdown__menu-item" id>​…