add qt 55 install, update readme for xcode install

Author: adrienatallah

README.md

@@ -16,10 +16,12 @@ We support:
 
 * [OS X Yosemite (10.10)](https://www.apple.com/osx/)
 
-Older versions may work but aren't regularly tested. Bug reports for older
-versions are welcome.
+    _Older OS X versions may work but aren't regularly tested. Bug reports for older
+versions are welcome._
 
-* [Xcode]:(https://itunes.apple.com/us/app/xcode/id497799835) must be installed.
+* [XCode version 9.4](https://developer.apple.com/download/more/?name=Xcode) (requires Apple ID login)
+
+    _Latest version of XCode may cause build problems with Qt 5.5 and capybara.  XCode version 9.4 is recommended.  For instructions on downgrading versions see [this article](https://medium.com/@tseboho/how-to-downgrade-xcode-4359df5158d5)._
 
 Base Install
 -------
@@ -62,6 +64,8 @@ With Xcode 8.0, when trying to compile the gem you may get the error Project ERR
 
 _For further reading: https://github.com/thoughtbot/capybara-webkit/wiki/Installing-Qt-and-compiling-capybara-webkit#macos-sierra-1012_
 
+_Details for manual install of Qt 5.5: https://github.com/thoughtbot/capybara-webkit/wiki/Installing-Qt-and-compiling-capybara-webkit#macos-high-sierra-1013-macos-sierra-1012-el-capitan-1011-and-yosemite-1010_
+
 kutil Install
 --------------
 ```sh

mac.sh

@@ -206,6 +206,17 @@ install_postgresql() {
   fi
 }
 
+install_qt55() {
+  cd  `brew --prefix`/Homebrew/Library/Taps/homebrew/homebrew-core
+  git fetch --unshallow
+  git checkout 9ba3d6ef8891e5c15dbdc9333f857b13711d4e97 Formula/[email protected]
+  cd -
+
+  brew_install_or_upgrade '[email protected]'
+
+  append_to_zshrc 'export PATH="$(brew --prefix [email protected])/bin:$PATH"'
+}
+
 ##### Start Installation #####
 
 if [ ! -d "$HOME/.bin/" ]; then
@@ -235,8 +246,6 @@ brew_install_or_upgrade 'ctags'
 brew_install_or_upgrade 'tmux'
 brew_install_or_upgrade 'reattach-to-user-namespace'
 brew_install_or_upgrade 'imagemagick'
-brew_install_or_upgrade 'qt55'
-brew link --force qt55
 brew_install_or_upgrade 'fswatch'
 brew_install_or_upgrade 'unison'
 brew_install_or_upgrade 'hub'
@@ -260,6 +269,12 @@ brew_install_or_upgrade 'httpie'
 brew_install_or_upgrade 'z'
 brew_install_or_upgrade 'watchman'
 
+brew_tap 'homebrew/cask'
+cask_install_or_upgrade 'phantomjs'
+cask_install_or_upgrade 'chromedriver'
+install_elasticsearch
+install_qt55
+
 # Install applications
 cask_install_or_upgrade 'macvim'
 cask_install_or_upgrade 'google-chrome'
@@ -272,11 +287,7 @@ cask_install_or_upgrade 'xquartz'
 cask_install_or_upgrade 'sublime-text'
 cask_install_or_upgrade '1password'
 cask_install_or_upgrade 'alfred'
-brew_tap 'homebrew/cask'
-cask_install_or_upgrade 'phantomjs'
-cask_install_or_upgrade 'chromedriver'
 install_shift_it
-install_elasticsearch
 install_latest_ruby
 install_vim_config