AttributeError when selecting timeseries

[petter-memrise]

Make sure these boxes are checked before submitting your issue - thank you!

• [ x ] I have checked the caravel logs for python stacktraces and included it here as text if any
• [ x ] I have reproduced the issue with at least the latest released version of caravel
• [ x ] I have checked the issue tracker for the same issue and I haven't found one similar

Caravel version

0.11.0

Expected results

A line chart over time should be shown

Actual results

When executing query in the SQL editor it gives correct results, but when clicking Visualize, choosing Time Series - Line Chart, it gives the following stacktrace:

2016-10-28 12:04:51,900:INFO:root:Running query: 
SELECT * 
FROM (SELECT 
    DATE(created_on) as date, 
    metric_name metric, 
    count(1) number
FROM sql_metrics
group by 
    DATE(created_on), 
    metric_name
order by 
    DATE(created_on), 
    metric_name) AS inner_qry
 LIMIT 1000 OFFSET 0
2016-10-28 12:04:59,429:DEBUG:MARKDOWN:Successfuly imported extension module "markdown.extensions.tables".
2016-10-28 12:04:59,429:DEBUG:MARKDOWN:Successfully loaded extension "markdown.extensions.tables.TableExtension".
2016-10-28 12:04:59,430:DEBUG:MARKDOWN:Successfuly imported extension module "markdown.extensions.fenced_code".
2016-10-28 12:04:59,430:DEBUG:MARKDOWN:Successfully loaded extension "markdown.extensions.fenced_code.FencedCodeExtension".
2016-10-28 12:04:59,430:DEBUG:MARKDOWN:Successfuly imported extension module "markdown.extensions.codehilite".
2016-10-28 12:04:59,430:DEBUG:MARKDOWN:Successfully loaded extension "markdown.extensions.codehilite.CodeHiliteExtension".
2016-10-28 12:05:00,155:ERROR:root:'TextClause' object has no attribute 'join'
Traceback (most recent call last):
  File "/Users/petter/.virtualenvs/caravel_test/lib/python2.7/site-packages/caravel/views.py", line 1183, in explore
    viz_obj.get_json(),
  File "/Users/petter/.virtualenvs/caravel_test/lib/python2.7/site-packages/caravel/viz.py", line 318, in get_json
    'data': self.get_data(),
  File "/Users/petter/.virtualenvs/caravel_test/lib/python2.7/site-packages/caravel/viz.py", line 1126, in get_data
    df = self.get_df()
  File "/Users/petter/.virtualenvs/caravel_test/lib/python2.7/site-packages/caravel/viz.py", line 1028, in get_df
    df = super(NVD3TimeSeriesViz, self).get_df(query_obj)
  File "/Users/petter/.virtualenvs/caravel_test/lib/python2.7/site-packages/caravel/viz.py", line 165, in get_df
    self.results = self.datasource.query(**query_obj)
  File "/Users/petter/.virtualenvs/caravel_test/lib/python2.7/site-packages/caravel/models.py", line 937, in query
    tbl = tbl.join(subq.alias(), and_(*on_clause))
AttributeError: 'TextClause' object has no attribute 'join'

Steps to reproduce

Run a query with one date column, one dimension and one aggregated field (grouped by date + dimension) (see test query above).

[mistercrunch]

Fixed in master