fix SDES encryption

[MilanKral]

This is a possible fix for the issue:

No static method decodeBase64(Ljava/lang/String;)[B in class Lorg/apache/commons/codec/binary/Base64; or its super classes

#91

After the fix SDES works correctly.

The library ch.imvs.sdes4j is directly included in the source code.
Imports for org.apache.commons.codec.binary are replaced with
a local copy org2.apache.commons.codec.binary .

[cmeng-git]

You do not need to include the whole sdes4j source into aTalk project but uses the jarjar tool to rename the reference class name in sdes4j. Then just include the newly re-reference class into aTalk project directory. i.e. just copy apache Base64 class and rename to ApacheBase64 (new reference from sde4j) into aTalk project. I have already implemented this fix and will be in next aTalk release.

========== aTalk build.gradle ===========
    // implementation 'ch.imvs:sdes4j:1.1.4'
    // libraries from maven repository but need to change Base64 to ApacheBase64 to avoid conflict with android
    // declaration of 'org.apache.commons.codec.binary.Base64' appears in /system/framework/org.apache.http.legacy.boot.jar
    implementation jarjar.repackage {
        from('ch.imvs:sdes4j:1.1.4') {
            transitive = false
        }
        destinationDir new File("${projectDir}/libs")
        destinationName "sde4j-1.1.4.jar"

        classRename 'org.apache.commons.codec.binary.Base64', 'org.apache.commons.codec.binary.ApacheBase64'
    }

[MilanKral]

ok, I will then close the pull request