Prefix all syntax error messages

Issue sds#232 requested that `scss-lint` give some indication of whether an
error was syntax- or style-related so that it would be displayed
appropriately by the Syntastic scss-lint plugin.

Since the only syntax error will ever be one reported by the `Runner`
class when parsing the document fails, standardize the error message to
being with "Syntax Error", so the scss-lint plugin can simply check the
error message to determine whether it is style or syntax.

Change-Id: I90183af30adba900ebcf94f688b8991ddcc1b663
Reviewed-on: http://gerrit.causes.com/44340
Tested-by: jenkins <[email protected]>
Reviewed-by: Shane da Silva <[email protected]>

Author: sds

Diff for: CHANGELOG.md

@@ -38,6 +38,7 @@
   the `--format` flag to be redirected to a file
 * Add `--require` flag allowing arbitrary Ruby modules to be loaded (facilitating
   custom reporters)
+* Prefix all syntax error messages with "Syntax Error:"
 
 ## 0.29.0
 

Diff for: lib/scss_lint/runner.rb

@@ -48,7 +48,8 @@ def find_lints(file)
         end
       end
     rescue Sass::SyntaxError => ex
-      @lints << Lint.new(nil, ex.sass_filename, Location.new(ex.sass_line), ex.to_s, :error)
+      @lints << Lint.new(nil, ex.sass_filename, Location.new(ex.sass_line),
+                         "Syntax Error: #{ex}", :error)
     rescue FileEncodingError => ex
       @lints << Lint.new(nil, file, Location.new, ex.to_s, :error)
     end