increase bower timeout

default timeout 60 seconds is too low

```
$ app/console avanzu:admin:fetch-vendor
[Executing] /home/glen/scm/delfi/mds/app/../bin/bowerphp install
[Progress] bower jquery#*             
[Progress] bower jquery#2.1.1             install
[Progress] bower jquery-ui#*          
[Progress] bower jquery-ui#1.11.0         install
[Progress] bower momentjs#*           
[Progress] bower momentjs#2.8.0           install
[Progress] bower backbone#*           
[Progress] bower backbone#1.1.2           install
[Progress] bower underscore#>=1.5.0   


                                                                                                          
  [Symfony\Component\Process\Exception\ProcessTimedOutException]                                          
  The process "/home/glen/myapp/app/../bin/bowerphp install" exceeded the timeout of 60 seconds.  
                                                                                                          


avanzu:admin:fetch-vendor [-u|--update]
```