Fix layout on Apple devices

The layout issue was related to the lack of autoprexing for CSS
properties. c69f993 did improve the reload time significantly but for
that I had to replace `mquandalle:stylus` by the core `stylus`
package. Unfortunatly it is currently difficult to run an autoprefixer
with the core CSS compilers (as reported in
https://github.com/meteor/meteor/issues/5219).

So instead we rely on `nib` which transparently define some mixins for
autoprefixing, the only restrictions being that we have to manually
`@import 'nib'` on top of stylus files.

Fixes #461

client/components/activities/activities.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 .activities
   clear: both
 

client/components/activities/comments.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 .new-comment
   position: relative
   margin: 0 0 20px 38px

client/components/boards/boardsList.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 $spaceBetweenTiles = 16px
 
 .board-list

client/components/cards/attachments.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 .attachments-galery
   display: flex
   flex-wrap: wrap

client/components/cards/minicard.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 .minicard-wrapper
   cursor: pointer
   position: relative

client/components/import/import.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 .map-members
   .mapping:first-of-type
     border-top: solid 1px #999

client/components/main/spinner.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 /*
  * From https://github.com/tobiasahlin/SpinKit
  *

client/components/users/userForm.styl

@@ -1,3 +1,5 @@
+@import 'nib'
+
 .auth-layout
   .at-form-landing-logo
     width: 249px