fix(Markdown): render markdown in more secure way

This commit changes markdown sanitization behaviour in following way:

class, style and data-* attributes are removed by default. These attributes
open possible vulnerability vectors to attackers.

The original behavior of sanitizer (before this commit) can be enabled by *useUnsafeMarkdown* configuration option.
Use this configuration option with caution and only in cases when you know
what you're doing.

src/core/components/auth/api-key-auth.jsx

@@ -44,7 +44,7 @@ export default class ApiKeyAuth extends React.Component {
     const Row = getComponent("Row")
     const Col = getComponent("Col")
     const AuthError = getComponent("authError")
-    const Markdown = getComponent( "Markdown" )
+    const Markdown = getComponent("Markdown", true)
     const JumpToPath = getComponent("JumpToPath", true)
     let value = this.getValue()
     let errors = errSelectors.allErrors().filter( err => err.get("authId") === name)