re: #968 Continue configure.sh even if apt-get failed.

Issue #968 is about a failed `apt-get update`; the packages installed via `apt-get install` are crucial for program function. Thus, the script shouldn't ignore the exit values of the `apt-get install` commands.

Suggest removing the `set +- e` commands and replacing the `sudo apt-get update` command with:
```bash
sudo apt-get -q update || echo 'Failed to fetch updated package list. Continuing...'
```