Removed syntastic and replaced it with ale

Read more here:
https://github.com/w0rp/ale

sources_non_forked/ale/doc/ale-r.txt

@@ -0,0 +1,29 @@
+===============================================================================
+ALE R Integration                                               *ale-r-options*
+
+
+===============================================================================
+lintr                                                             *ale-r-lintr*
+
+g:ale_r_lintr_options                                   *g:ale_r_lintr_options*
+                                                        *b:ale_r_lintr_options*
+  Type: |String|
+  Default: `'lintr::with_defaults()'`
+
+  This option can be configured to change the options for lintr.
+
+  The value of this option will be run with `eval` for the `lintr::lint`
+  options. Consult the lintr documentation for more information.
+
+
+g:ale_r_lintr_lint_package                         *g:ale_r_lintr_lint_package*
+                                                   *b:ale_r_lintr_lint_package*
+  Type: |Number|
+  Default: `0`
+
+  When set to `1`, the file will be checked with `lintr::lint_package` instead
+  of `lintr::lint`. This prevents erroneous namespace warnings when linting 
+  package files.
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl: