Maid-315_update_data_manager_account_rebase

Based on the work from MAID-304.
1, trim DataManager account
2, update corresponding persona logical due to trimmed account in DM and PM
3, remove un-necessary class, action, etc.
4, comment out outdated tests
David mentioned there shall be no difference between online and offline pmids regarding stored account.

the new algorithm regarding removing from list is : 
when the list reaching the cap (group_size), then remove the furthest offline node to the chunk
chunk the commit of https://github.com/maqi/MaidSafe-Vault/commit/802bedc171a7fa2b588ac96cccd732d7632c2be8
for the detailed implementation of the algorithm

change it back to differentiate online/offline will have revert the majority of the work in this pull request.