Fix Admin Authentication Support

[jordanaubert]

Related issue : api-platform/admin#165

ATM, using the latest version of the admin with the current documentation lead to this error when there is no token in the local storage :

Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

    in Switch (created by RoutesWithLayout)
    in RoutesWithLayout (created by Route)
    in div (created by Layout)
    in main (created by Layout)
    in div (created by Layout)
    in div (created by Layout)
    in Layout (created by WithStyles(Layout))
    in WithStyles(Layout) (created by Route)
    in Route (created by withRouter(WithStyles(Layout)))
    in withRouter(WithStyles(Layout)) (created by Connect(withRouter(WithStyles(Layout))))
    in Connect(withRouter(WithStyles(Layout))) (created by LayoutWithTheme)
    in MuiThemeProvider (created by LayoutWithTheme)
    in LayoutWithTheme (created by Route)
    in Route (created by CoreAdminRouter)
    in Switch (created by CoreAdminRouter)
    in div (created by CoreAdminRouter)
    in CoreAdminRouter (created by Connect(CoreAdminRouter))
    in Connect(CoreAdminRouter) (created by getContext(Connect(CoreAdminRouter)))
    in getContext(Connect(CoreAdminRouter)) (created by Route)
    in Route (created by CoreAdminBase)
    in Switch (created by CoreAdminBase)
    in Router (created by ConnectedRouter)
    in ConnectedRouter (created by CoreAdminBase)
    in TranslationProviderView (created by Connect(TranslationProviderView))
    in Connect(TranslationProviderView) (created by CoreAdminBase)
    in Provider (created by CoreAdminBase)
    in CoreAdminBase (created by withContext(CoreAdminBase))
    in withContext(CoreAdminBase) (created by AdminBuilder)
    in AdminBuilder (created by _default)
    in _default (at App.js:39)
    in App (at src/index.js:7)

[alanpoulain]

I would keep the variable.

[jordanaubert]

I did so because my linter said it shadowed the entrypoint prop of apiDocumentationParser

[alanpoulain]

Thank you @jordanaubert!