VIVO-333 External-auth login button should be language-sensitive.

Don't specify the text in the runtime.properties. Instead, get it from all.properties. Show the button if externalAuth.netIdHeaderName is specified.

webapp/web/i18n/all.properties

@@ -661,6 +661,7 @@ javascript_require_to_edit = In order to edit content, you'll need to enable Jav
 javascript_instructions = java script instructions
 to_enable_javascript = Here are the instructions for enabling JavaScript in your web browser
 external_auth_name = external authentication name
+external_login_text = Log in using BearCat Shibboleth 
 account = account
 change_password_to_login = Change Password to Log in
 new_password_capitalized = New Password

webapp/web/templates/freemarker/widgets/widget-login.ftl

@@ -47,7 +47,7 @@
             <#if externalAuthUrl??>
                 <#assign infoClassHide = 'class="vivoAccount"'/>
             
-                <p class="external-auth"><a class="blue button" href="${externalAuthUrl}" title="${i18n().external_auth_name}">${externalAuthName}</a></p>
+                <p class="external-auth"><a class="blue button" href="${externalAuthUrl}" title="${i18n().external_auth_name}">${i18n().external_login_text}</a></p>
                 <!--<p class="or-auth">or</p>-->
                 <h3 class="internal-auth"><!--Log in using your--> <b>${i18n().or}</b> ${siteName} ${i18n().account}</h3>