require-space-after-line-comment: add except option

according to jscs-dev#592 and jscs-dev#593 we've decided to make allExcept option to this rule to pass there a list of allowed characters

- added allExcept option to pass here exceptions
- fixes initial jscs-dev#592 bug with tabs in line comments
- add validation of allExcept (should be a <String[]>, according to jscs-dev#698)

Closes jscs-dev#696
Fixes jscs-dev#592

lib/rules/require-space-after-line-comment.js

@@ -7,11 +7,25 @@ module.exports.prototype = {
     configure: function(requireSpaceAfterLineComment) {
         assert(
             requireSpaceAfterLineComment === true ||
-            requireSpaceAfterLineComment === 'allowSlash',
-            'requireSpaceAfterLineComment option requires the value true or `allowSlash`'
+            requireSpaceAfterLineComment === 'allowSlash' ||
+            typeof requireSpaceAfterLineComment === 'object',
+            'requireSpaceAfterLineComment option requires the value `true` ' +
+            'or an object with String[] `allExcept` property'
         );
 
-        this._allowSlash = requireSpaceAfterLineComment === 'allowSlash';
+        // verify first item in `allExcept` property in object (if it's an object)
+        assert(
+            typeof requireSpaceAfterLineComment !== 'object' ||
+            Array.isArray(requireSpaceAfterLineComment.allExcept) &&
+            typeof requireSpaceAfterLineComment.allExcept[0] === 'string',
+            'Property `allExcept` in requireSpaceAfterLineComment should be an array of strings'
+        );
+
+        // don't check triple slashed comments, microsoft js doc convention. see #593
+        // exceptions. see #592
+        // need to drop allowSlash support in 2.0. Fixes #697
+        this._allExcept = requireSpaceAfterLineComment === 'allowSlash' ? ['/'] :
+            requireSpaceAfterLineComment.allExcept || [];
     },
 
     getOptionName: function() {
@@ -20,21 +34,26 @@ module.exports.prototype = {
 
     check: function(file, errors) {
         var comments = file.getComments();
-        var allowSlash = this._allowSlash;
+        var allExcept = this._allExcept;
 
         comments.forEach(function(comment) {
             if (comment.type === 'Line') {
                 var value = comment.value;
 
-                // don't check triple slashed comments, microsoft js doc convention. see #593
-                if (allowSlash && value[0] === '/') {
-                    value = value.substr(1);
-                }
+                // cutout exceptions
+                allExcept.forEach(function(el) {
+                    if (value.indexOf(el) === 0) {
+                        value = value.substr(el.length);
+                    }
+                });
 
                 if (value.length === 0) {
                     return;
                 }
 
+                // tabs should be treated as spaces. see #592
+                value = value.replace(/[\s]/g, ' ');
+
                 if (value[0] !== ' ') {
                     errors.add('Missing space after line comment', comment.loc.start);
                 }