#145 ignore empty questions inserting editing intents

[Miguel-Alves]

According to the needs of #145, this PR is solving the problems described.

• Now, when inserting or editting an intent, the user can leave empty ballons (as longs as they are not the only content), so it continues to stimulate him to add more content;
• Empty ballons are not saved to the database anymore;
• If present, empty balloons are removed from the utters upon loading;

This Pull Request resolves #145

[gabibguedes]

I couldn't get it to work properly, it still doesn't let me save intents with empty baloons.

[gabibguedes]

Change it back to the env variable, with it we can set the API endpoint on production environments

[Miguel-Alves]

@gabibguedes are you using the dev environment or the docker?
Until the docker problem is solved, using the docker is not possible cause it doesnt reflect changes we made to the code.
Also, as the docker doesnt work properly, we need this variable set this way as described on #157