Apply new-lines check to all lines of a file, not just the first one

fixes adrienverge#475

yamllint/rules/new_lines.py

@@ -51,8 +51,8 @@ def check(conf, line):
     elif conf['type'] == 'dos':
         newline_char = '\r\n'
 
-    if line.start == 0 and len(line.buffer) > line.end:
+    if len(line.buffer) > line.end:
         if line.buffer[line.end:line.end + len(newline_char)] != newline_char:
             c = repr(newline_char).strip('\'')
-            yield LintProblem(1, line.end - line.start + 1,
+            yield LintProblem(line.line_no, line.end - line.start + 1,
                               f'wrong new line character: expected {c}')