Remove only tail comment

[yusukegoto]

The fix of #14 replace lines with tail comment with empty line.
I made patch to remove only tail comment from line.

Example: definition used has a tail comment.

Original lines

=> ["import UIKit\n",
 "\n",
 "class TestView: UIView {\n",
 "  var used = \"\" // should not be ignored\n",
 "  var unused = \"\"\n",
 "\n",
 "  override init(frame: CGRect) {\n",
 "    print(used)\n",
 "    super.init(frame: frame)\n",
 "  }\n",
 "}\n"]

Before fix; definition used is replaced with ''

=> ["import UIKit\n",
 "\n",
 "class TestView: UIView {\n",
 "\n",
 "  var unused = \"\"\n",
 "\n",
 "  override init(frame: CGRect) {\n",
 "    print(used)\n",
 "    super.init(frame: frame)\n",
 "  }\n",
 "}\n"]

After fix

=> ["import UIKit\n",
 "\n",
 "class TestView: UIView {\n",
 "  var used = \"\" \n",
 "  var unused = \"\"\n",
 "\n",
 "  override init(frame: CGRect) {\n",
 "    print(used)\n",
 "    super.init(frame: frame)\n",
 "  }\n",
 "}\n"]