Exclude everthing Punycode related (apparently those classes were excluded from Android release); remove SPNEGO and Kerberos auth schemes; added rewrite task for Base64 encoding

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient-android/trunk@1557796 13f79535-47bb-0310-9956-ffa450edef68