added functionality restore original jQuery

If page already had jQuery, reset to that jQuery when `resetjQuery` is
called. Otherwise completely remove jQuery from this window
added functionality restore original jQuery

If page already had jQuery, reset to that jQuery when `resetjQuery` is
called. Otherwise completely remove jQuery from this window
Merge branch 'load_specific_jquery' of https://github.com/yawboakye/devtools-snippets into load_specific_jquery
Merge branch 'master' of https://github.com/yawboakye/devtools-snippets