Fix system overview edit hostname form validation

- Add pattern for no spaces
- Fix character count
- Prepopulate hostname in input field
- Show error for invalid input
- Improve form accessibility
- Correct global disabled primary button style

Resolves openbmc/phosphor-webui#71

Signed-off-by: Dixsie Wolmers <dixsiew@gmail.com>
Change-Id: Ia0601ac7c52229d0606dc5b13397b468fa81426d
diff --git a/app/common/styles/base/buttons.scss b/app/common/styles/base/buttons.scss
index 31b72ff..70b70cc 100644
--- a/app/common/styles/base/buttons.scss
+++ b/app/common/styles/base/buttons.scss
@@ -11,7 +11,6 @@
     cursor: pointer;
   }
   &.disabled {
-    opacity: 0.2;
     color: $btn__disabled-txt;
     &:hover {
       cursor: default;
@@ -30,8 +29,8 @@
     @include fastTransition-all;
   }
   &.disabled {
-    background: $btn__disabled-bg;
-    color: $btn__disabled-txt;
+    background: $primebtn__disabled-bg;
+    color: $primebtn__disabled-txt;
     @include fastTransition-all;
     &:hover {
       cursor: default;