Problem: Doing a custom query after a time range is selected leads to URL parameter error: ``` http://localhost:5000/query/?time=2016?bql=balances%20from%20year%20%3D%202015%3B ``` The second ? should be &.
Problem:
Doing a custom query after a time range is selected leads to URL parameter error:
```
http://localhost:5000/query/?time=2016?bql=balances%20from%20year%20%3D%202015%3B
```
The second ? should be &.

Root cause:
The code to construct the redirect URL hardcodes the `?`.

Solution:
Check for the existance of a `?` in the URL. If it exists, use `&` instead.

yagebu/fava,beancount/fava,aumayr/beancount-web,corani/beancount-web,beancount/fava,yagebu/fava,aumayr/beancount-web,corani/beancount-web,beancount/fava,yagebu/fava,yagebu/fava,yagebu/fava,beancount/fava,aumayr/beancount-web,corani/beancount-web,corani/beancount-web,beancount/fava,aumayr/beancount-web