Replace mentions of easy_install by pip

Use this chance to correct minor typos.

Closes Homebrew/homebrew#15242.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Library/Homebrew/blacklist.rb

@@ -29,9 +29,7 @@ def blacklisted? name
     We recommend using a MacTeX distribution: http://www.tug.org/mactex/
     EOS
   when 'pip' then <<-EOS.undent
-    Install pip with easy_install:
-
-        easy_install pip
+    pip is installed by `brew install python`
     EOS
   when 'macruby' then <<-EOS.undent
     MacRuby works better when you install their package:

Library/Homebrew/dependencies.rb

@@ -185,7 +185,7 @@ class LanguageModuleDependency < Requirement
       when :lua     then "luarocks install"
       when :node    then "npm install"
       when :perl    then "cpan -i"
-      when :python  then "easy_install"
+      when :python  then "pip install"
       when :rbx     then "rbx gem install"
       when :ruby    then "gem install"
     end