base 64 helper functions for Dbus

implement alternate versions of commands that take a Group Id in
the form of byte[] to permit passing a string in base 64 format.

Methods affected:
- getGroupIds
- getGroupMembers
- getGroupName
- isGroupBlocked
- isMember
- quitGroup
- sendGroupMessage
- sendGroupMessageReaction
- sendGroupRemoteDeleteMessage
- setGroupBlocked
- updateGroup

Implement new helper function specifically for base 64 identifiers:
- getGroupIdsBase64()

Update and reorganize Dbus API documentation.

.gitignore

@@ -1,3 +1,4 @@
+.gitignore
 .gradle/
 .idea/*
 !.idea/codeStyles/
@@ -11,3 +12,6 @@ local.properties
 .settings/
 out/
 .DS_Store
+.asciidoctorconfig.adoc
+patches/
+signal-cli