remove strict requirement for less,invoke in wheel/sdist

move the strictness to our release script

this means others can build personal wheels without less, invoke,
but IPython releases still cannot be made without them,
which is the real goal.

setup.py

@@ -216,7 +216,7 @@ setup_args['cmdclass'] = {
     'build_py': css_js_prerelease(
             check_package_data_first(git_prebuild('IPython')),
         strict=False),
-    'sdist' : css_js_prerelease(git_prebuild('IPython', sdist)),
+    'sdist' : css_js_prerelease(git_prebuild('IPython', sdist), strict=False),
     'upload_wininst' : UploadWindowsInstallers,
     'submodule' : UpdateSubmodules,
     'css' : CompileCSS,
@@ -284,7 +284,7 @@ if 'setuptools' in sys.modules:
     # setup.py develop should check for submodules
     from setuptools.command.develop import develop
     setup_args['cmdclass']['develop'] = require_submodules(develop)
-    setup_args['cmdclass']['bdist_wheel'] = css_js_prerelease(get_bdist_wheel())
+    setup_args['cmdclass']['bdist_wheel'] = css_js_prerelease(get_bdist_wheel(), strict=False)
     
     setuptools_extra_args['zip_safe'] = False
     setuptools_extra_args['entry_points'] = {'console_scripts':find_entry_points()}