implements bot info method

[fabio-ivona]

Adds a botInfo method to Telegraph class

this will allow to retrieve a bot's data from telegraph APIs:

$bot->info()

/*
id: xxxxx
is_bot: true
first_name: telegraph-test
username: my_test_bot
can_join_groups: true
can_read_all_group_messages: false
supports_inline_queries: false
*/