DataTable loading delayed in some views

[Rigueur]

Is your feature request related to a problem? Please describe.

The loading of filters and other DataTable functions is delayed on some screens (such as users > email accounts) which creates visual discomfort for the users.

Describe the solution you'd like

The tools shouldnt be charged so long after the table but displayed at the same time as the table

[marien-probesys]

I suggested in https://github.com/Probesys/agentj/issues/142 to replace Datatable with pagination on the server side with KnpPaginatorBundle (as it is done for the messages views). It should drastically improve the performance on big volumes of data, and fix this issue at the same time.

[marien-probesys]

Closing in favor of #142