Change style of alert message field to be more consistent with inputs

ui/src/kapacitor/components/RuleMessageText.js

@@ -1,13 +1,15 @@
 import React, {PropTypes} from 'react'
 
 const RuleMessageText = ({rule, updateMessage}) =>
-  <textarea
-    className="form-control form-malachite monotype rule-builder--message"
-    onChange={updateMessage}
-    placeholder="Example: {{ .ID }} is {{ .Level }} value: {{ index .Fields &quot;value&quot; }}"
-    value={rule.message}
-    spellCheck={false}
-  />
+  <div className="rule-builder--message">
+    <textarea
+      className="form-control form-malachite monotype"
+      onChange={updateMessage}
+      placeholder="Example: {{ .ID }} is {{ .Level }} value: {{ index .Fields &quot;value&quot; }}"
+      value={rule.message}
+      spellCheck={false}
+    />
+  </div>
 
 const {func, shape} = PropTypes
 

ui/src/style/pages/kapacitor.scss

@@ -307,23 +307,15 @@ $rule-builder--radius-lg: 5px;
   Section 3 - Rule Message
   -----------------------------------------------------------------------------
 */
-
-textarea.rule-builder--message {
-  border-color: $rule-builder--section-bg;
+.rule-builder--message {
   background-color: $rule-builder--section-bg;
   padding: $rule-builder--padding-sm ($rule-builder--padding-lg - 2px);
+}
+.rule-builder--message textarea {
   height: 100px;
   min-width: 100%;
   max-width: 100%;
-  border-radius: 0;
   @include custom-scrollbar($rule-builder--section-bg,$rule-builder--accent-color);
-
-  &:hover {
-    border-color: $g4-onyx;
-  }
-  &:focus {
-    background-color: $rule-builder--section-bg;
-  }
 }
 .rule-builder--message-template {
   height: 30px;