Avoid line continuations without parentheses.

This causes unexpected behaviour: The `not_to` spec will always pass,
whilst the `to include` specs don't test for the presence of the command
line, rather nothing. This is because Ruby treats the `include` as having no
argument and the string below as a string literal.

If we wrap in parentheses, the positive spec fails as the path is
relative to the root partition.

The solution here is to provide a full path when comparing
`gemfile='...'`. This also fixes a broken expectation where `not_to` and
`to` were flipped.

spec/acceptance/cli/install_spec.rb

@@ -36,8 +36,8 @@
 
     run 'appraisal install'
 
-    expect(content_of 'gemfiles/1.0.0.gemfile.lock').not_to include
-      current_directory
+    expect(content_of("gemfiles/1.0.0.gemfile.lock")).
+      not_to include(current_directory)
   end
 
   context 'with job size', :parallel => true do
@@ -52,19 +52,24 @@
     it 'accepts --jobs option to set job size' do
       output = run 'appraisal install --jobs=2'
 
-      expect(output).to include
-        'bundle install --gemfile=gemfiles/1.0.0.gemfile --jobs=2'
+      expect(output).to include(
+        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=2"
+      )
     end
 
     it 'ignores --jobs option if the job size is less than or equal to 1' do
       output = run 'appraisal install --jobs=0'
 
+      expect(output).
+        to include(
+        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}'"
+      )
       expect(output).not_to include(
-        'bundle install --gemfile=gemfiles/1.0.0.gemfile')
+        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=0"
+      )
       expect(output).not_to include(
-        'bundle install --gemfile=gemfiles/1.0.0.gemfile --jobs=0')
-      expect(output).not_to include(
-        'bundle install --gemfile=gemfiles/1.0.0.gemfile --jobs=1')
+        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=1"
+      )
     end
   end
 end