Add implementation date and version

[codeurimpulsif]

Goal

• Add implementation_version and implementation_date fields.
• Add this informations for clients with 100 % OMEMO implementation

Fix #290

[Neustradamus]

@codeurimpulsif: Good job but can you add the OMEMO supported version too?

cc: @bascht.

[Neustradamus]

@codeurimpulsif: One number is missing for weechat-xmpp and some have not date :/

[codeurimpulsif]

@codeurimpulsif: Good job but can you add the OMEMO supported version too?

Would be cool yes, but I will wait this PR merge to do this.

@codeurimpulsif: One number is missing for weechat-xmpp and some have not date :/

If some have no dates or other informations it's because I can't find them.