Add support for --path option to install

This allows installing Neat into a specific directory.
It's more consistent with Bourbon CLI

Fix #351

README.md

@@ -45,6 +45,12 @@ For command line help, visit our wiki page on Neat’s [command line interface](
   neat install
   ```
 
+  **Pro Tip:** You can target installation into a specific directory using the `path` flag:
+
+  ```bash
+  neat install --path my/custom/path/
+  ```
+
 4. Import Neat in your stylesheet:
 
   ```scss

lib/neat/generator.rb

@@ -7,16 +7,18 @@ class Generator < Thor
     map ["-v", "--version"] => :version
 
     desc "install", "Install Neat into your project"
+    method_options :path => :string, :force => :boolean
     def install
-      if neat_files_already_exist?
+      if neat_files_already_exist? && !options[:force]
         puts "Neat files already installed, doing nothing."
       else
         install_files
-        puts "Neat files installed to neat/"
+        puts "Neat files installed to #{install_path}/"
       end
     end
 
     desc "update", "Update Neat"
+    method_options :path => :string
     def update
       if neat_files_already_exist?
         remove_neat_directory
@@ -28,6 +30,7 @@ def update
     end
 
     desc "remove", "Remove Neat"
+    method_options :path => :string
     def remove
       if neat_files_already_exist?
         remove_neat_directory
@@ -45,16 +48,32 @@ def version
     private
 
     def neat_files_already_exist?
-      File.directory?("neat")
+      install_path.exist?
     end
 
-    def install_files
-      FileUtils.mkdir_p("neat")
-      FileUtils.cp_r(all_stylesheets, "neat/")
+    def install_path
+      @install_path ||= if options[:path]
+          Pathname.new(File.join(options[:path], 'neat'))
+        else
+          Pathname.new('neat')
+        end
     end
 
     def remove_neat_directory
-      FileUtils.rm_rf("neat")
+      FileUtils.rm_rf(install_path)
+    end
+
+    def install_files
+      make_install_directory
+      copy_in_scss_files
+    end
+
+    def make_install_directory
+      FileUtils.mkdir_p(install_path)
+    end
+
+    def copy_in_scss_files
+      FileUtils.cp_r(all_stylesheets, install_path)
     end
 
     def all_stylesheets