Use different reporter to support older versions of jscs (#737)

* Use different reporter to support older versions of jscs

* Add test and make more consistent with other code

* Add documentation for jscs

* Add more test coverage

test/command_callback/test_jscs_command_callback.vader

@@ -0,0 +1,25 @@
+Before:
+  runtime ale_linters/javascript/jscs.vim
+
+After:
+  call ale#linter#Reset()
+  let g:ale_javascript_jscs_executable = 'jscs'
+
+Execute(Should return the correct default values):
+  AssertEqual
+  \  'jscs',
+  \   ale_linters#javascript#jscs#GetExecutable(bufnr(''))
+  AssertEqual
+  \   '''jscs'' --reporter inline --no-colors -',
+  \   ale_linters#javascript#jscs#GetCommand(bufnr(''))
+
+
+Execute(Should allow using a custom executable):
+  let g:ale_javascript_jscs_executable = 'foobar'
+
+  AssertEqual
+  \   'foobar',
+  \   ale_linters#javascript#jscs#GetExecutable(bufnr(''))
+  AssertEqual
+  \   '''foobar'' --reporter inline --no-colors -',
+  \   ale_linters#javascript#jscs#GetCommand(bufnr(''))

test/handler/test_jscs_handler.vader

@@ -0,0 +1,25 @@
+
+Execute(jscs should parse lines correctly):
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 1,
+  \     'col': 7,
+  \     'text': 'disallowVar: Variable declarations should use `let` or `const` not `var`',
+  \   },
+  \   {
+  \     'lnum': 3,
+  \     'col': 21,
+  \     'text': 'disallowTrailingWhitespace: Illegal trailing whitespace',
+  \   },
+  \   {
+  \     'lnum': 5,
+  \     'col': 9,
+  \     'text': 'disallowUnusedVariables: Variable `hello` is not used',
+  \   },
+  \ ],
+  \ ale_linters#javascript#jscs#Handle(347, [
+  \   'foobar.js: line 1, col 7, disallowVar: Variable declarations should use `let` or `const` not `var`',
+  \   'foobar.js: line 3, col 21, disallowTrailingWhitespace: Illegal trailing whitespace',
+  \   'foobar.js: line 5, col 9, disallowUnusedVariables: Variable `hello` is not used',
+  \ ])