add return to if statements

[m4v15]

Here:
https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/modify_content.js#L65
https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/modify_content.js#L68
https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/modify_content.js#L54
https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/get_specific.js#L7
https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/delete_place.js#L12

Without returning these res.send's the code carries on adn can throw an error

[m4v15]

@Suuuuha So I realised when looking at another PR not all of these were fixed/there were some more. Can you go through all of your controller files and double check it's not happening anywhere else please...:

https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/get_specific.js#L13

https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/modify_content.js#L67

https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/modify_content.js#L78

https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/places/render_edit_form.js#L13

https://github.com/foundersandcoders/OTP-Data-Entry/blob/master/src/controllers/events/delete_event.js#L23

[m4v15]

This can be addressed at the same time as issue #53 probably