Add strava compatibility

[vibgy]

As a developer, I would love to be able to map the generated json to Strava easily. As of now, some key attributes that Strava looks at are missing from the JSON.
Ref: https://strava.github.io/api/v3/uploads/#file-types

Strava supports the following MESSAGE TYPES and ATTRIBUTES
file_id
--------    
manufacturer 
product 
time_created

session 
--------    
sport 
total_elapsed_time 
total_timer_time 
total_distance 
total_ascent

lap 
--------    
timestamp 
total_elapsed_time 
total_timer_time 
total_distance 
total_ascent

record  
--------    
timestamp 
position_lat 
position_long 
altitude 
heart_rate 
cadence 
distance 
power 
temperature 

event   
--------    
timestamp 
type 

Activity type is detected from session.sport.

[yocontra]

Which attributes are missing?

[vibgy]

Not much it seems. Perhaps just file_id and event maybe.