chimera easyblock

another tiny remark... it's better to do the `cd` part in Python code:

```python
try:
    os.chdir(self.cfg['start_dir'])
except OSError, err:
    self.log.error("Failed to change to %s: %s" % (self.cfg['start_dir'], err))

cmd = "./chimera.bin -q -d %s" % self.installdir
run_cmd(cmd, log_all=True, simple=True)
```