Resolve header and nav accessibility violations

- Add aria-label to nav sections in app-header and app-nav to meet
accessibility guidelines. When application has multiple nav elements
an aria-label is required to help screen readers identify the elements
- Remove b-nav child of b-nav-bar in app-header to fix invalid markup
generated by Bootstrap-vue components. Components were not used as
expected by the component library
- Replace b-nav-item with HTML <li> elements using nav-item css classes
in order to use button elements. Bootstrap-vue generates <a> elements
which is not the semantic HTML element to use for items that are not
links to other sections of the application.
- Removed aria-expanded and nav-open class from nav-trigger button
- Update appHeader unit test

Used a TDD approach to write all tests to fail and then updated the
methods and actions to make the tests suceed. Each test resulting in
a dispatched action should be called once only and with the expected
action.

Signed-off-by: Derick Montague <derick.montague@ibm.com>
Change-Id: I18af3727708526f814b7ceb77a0c28fda9f3d9bd
diff --git a/src/locales/en-US.json b/src/locales/en-US.json
index 22bb514..b243f53 100644
--- a/src/locales/en-US.json
+++ b/src/locales/en-US.json
@@ -36,6 +36,7 @@
     }
   },
   "appHeader": {
+    "applicationHeader": "Application header",
     "bmcSystemManagement": "BMC System Management",
     "health": "Health",
     "logOut": "Log out",
@@ -56,6 +57,7 @@
     "managePowerUsage": "@:appPageTitle.managePowerUsage",
     "networkSettings": "@:appPageTitle.networkSettings",
     "overview": "@:appPageTitle.overview",
+    "primaryNavigation": "Primary navigation",
     "rebootBmc": "@:appPageTitle.rebootBmc",
     "sensors": "@:appPageTitle.sensors",
     "serverLed": "@:appPageTitle.serverLed",