Add possibility to check current status 

It would be nice to have some command that displays info about current options set so user can double check is everything prepared correctly before sending request.  

eg
command: `h2c check-options`
output: 
```
connection: 123.123.123.123 
headers: 
  <Header1> : <value1> 
  <Header2> : <value2> 
data:  {} 
....
```
