Added NASM linter

Added NASM linter (for nasm filetype).

test/handler/test_nasm_handler.vader

@@ -0,0 +1,30 @@
+Before:
+  runtime ale_linters/nasm/nasm.vim
+
+After:
+  call ale#linter#Reset()
+
+Execute(The nasm handler should parse GCC style output from nasm correctly):
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 2,
+  \     'text': "label alone on a line without a colon might be in error",
+  \     'type': 'W',
+  \   },
+  \   {
+  \     'lnum': 4,
+  \     'text': "invalid combination of opcode and operands",
+  \     'type': 'E',
+  \   },
+  \   {
+  \     'lnum': 7,
+  \     'text': "unable to open include file `bar.asm'",
+  \     'type': 'E',
+  \   },
+  \ ],
+  \ ale_linters#nasm#nasm#Handle(357, [
+  \   "tmp.asm:2: warning: label alone on a line without a colon might be in error",
+  \   "tmp.asm:4: error: invalid combination of opcode and operands",
+  \   "tmp.asm:7: fatal: unable to open include file `bar.asm'"
+  \ ])