Update README.md

[kelset]

This is actually a pretty huge PR for the read me, bear with me:

• I've move around some parts, to make it more uniform.
• for the past meet ups sections I've set up a table, putting in only the actual speakers (in the old list there were also Mike Grabowski and Leland Richardson)
• for each speaker added a link to their twitter (all but Kumar, wasn't able to find his own so I put the NativeBaseIO one)
• added a reference to the suggestedTopics file ;)

[knowbody]

great stuff! Thank you!