Added new "white" theme

• Added:
- new "white" theme which makes navigation bar white and sets appropriate styles for children

app/javascript/gabsocial/components/navigation_bar/default_navigation_bar.js

@@ -171,7 +171,7 @@ class DefaultNavigationBar extends ImmutablePureComponent {
                     <div className={[_s.d, _s.h20PX, _s.w1PX, _s.mr10, _s.ml10, _s.bgNavigationBlend].join(' ')} />
 
                     <NavigationBarButton attrTitle='Notifications' icon='notifications' to='/notifications' />
-                    <NavigationBarButton attrTitle='Dark/Muted/Light Mode' icon='light-bulb' onClick={this.handleOnClickLightBulb} />
+                    <NavigationBarButton attrTitle='Dark/Muted/Light/White Mode' icon='light-bulb' onClick={this.handleOnClickLightBulb} />
 
                     <div className={[_s.d, _s.h20PX, _s.w1PX, _s.mr10, _s.ml10, _s.bgNavigationBlend].join(' ')} />
                   

app/javascript/gabsocial/components/navigation_bar/logged_out_navigation_bar.js

@@ -36,7 +36,7 @@ class LoggedOutNavigationBar extends React.PureComponent {
                 backgroundColor='none'
                 icon='logo'
                 title='Gab'
-                iconClassName={[_s.mr5, _s.fillNavigation].join(' ')}
+                iconClassName={[_s.mr5, _s.fillBrand].join(' ')}
               />
 
               {
@@ -64,8 +64,8 @@ class LoggedOutNavigationBar extends React.PureComponent {
               <Button
                 isNarrow
                 isOutline
-                color='white'
-                backgroundColor='none'
+                color='brand'
+                backgroundColor='white'
                 href='/auth/sign_in'
                 className={[_s.borderColorWhite, _s.mr5, _s.flexGrow1, _s.aiCenter, _s.jcCenter, _s.py7].join(' ')}
               >
@@ -76,8 +76,8 @@ class LoggedOutNavigationBar extends React.PureComponent {
 
               <Button
                 isNarrow
-                color='brand'
-                backgroundColor='white'
+                color='white'
+                backgroundColor='brand'
                 href='/auth/sign_up'
                 className={[_s.jcCenter, _s.aiCenter, _s.ml5, _s.flexGrow1, _s.py7].join(' ')}
               >