title: compute() in dask not working
body: <p>I am trying a simple parallel computation in Dask.
  This is my code.</p>
  
  <pre><code>  import time
    import dask as dask
    import dask.distributed as distributed
    import dask.dataframe as dd
    import dask.delayed as delayed
    from dask.distributed import Client,progress
  
    client = Client('localhost:8786')
    df = dd.read_csv('file.csv')
    ddf = df.groupby(['col1'])[['col2']].sum() 
    ddf = ddf.compute()
    print ddf
  </code></pre>
  
  <p>It seems fine from the documentation but on running I am getting this :</p>
  
  <pre><code>    Traceback (most recent call last):
      File "dask_prg1.py", line 17, in &lt;module&gt;
      ddf = ddf.compute()
      File "/usr/local/lib/python2.7/site-packages/dask/base.py", line 156, in compute
     (result,) = compute(self, traverse=False, **kwargs)
      File "/usr/local/lib/python2.7/site-packages/dask/base.py", line 402, in compute
     results = schedule(dsk, keys, **kwargs)
     File "/usr/local/lib/python2.7/site-packages/distributed/client.py", line 2159, in get
  direct=direct)
    File "/usr/local/lib/python2.7/site-packages/distributed/client.py", line 1562, in gather
  asynchronous=asynchronous)
   File "/usr/local/lib/python2.7/site-packages/distributed/client.py", line 652, in sync
  return sync(self.loop, func, *args, **kwargs)
   File "/usr/local/lib/python2.7/site-packages/distributed/utils.py", line 275, in sync
  six.reraise(*error[0])
   File "/usr/local/lib/python2.7/site-packages/distributed/utils.py", line 260, in f
  result[0] = yield make_coro()
     File "/usr/local/lib/python2.7/site-packages/tornado/gen.py", line 1099, in run
  value = future.result()
   File "/usr/local/lib/python2.7/site-packages/tornado/concurrent.py", line 260, in result
  raise_exc_info(self._exc_info)
   File "/usr/local/lib/python2.7/site-packages/tornado/gen.py", line 1107, in run
  yielded = self.gen.throw(*exc_info)
   File "/usr/local/lib/python2.7/site-packages/distributed/client.py", line 1439, in _gather
  traceback)
  File "/usr/local/lib/python2.7/site-packages/dask/bytes/core.py", line 122, in read_block_from_file
  with lazy_file as f:
  File "/usr/local/lib/python2.7/site-packages/dask/bytes/core.py", line 166, in __enter__
  f = SeekableFile(self.fs.open(self.path, mode=mode))
   File "/usr/local/lib/python2.7/site-packages/dask/bytes/local.py", line 58, in open
  return open(self._normalize_path(path), mode=mode)
   IOError: [Errno 2] No such file or directory: 'file.csv'
  </code></pre>
  
  <p>I am not understanding what is wrong.Kindly help me with this .Thank you in advance .</p>