Report spec

@jackparmer creating a PR to make adding commentary a bit easier!
yup, i think you could consider doing something similar to what we do for get subplots:

```
>>> fig = plotly.tools.get_subplots(7, 10, print_grid=True)
This is the format of your plot grid!
[61]    [62]    [63]    [64]    [65]    [66]    [67]    [68]    [69]    [70]    
[51]    [52]    [53]    [54]    [55]    [56]    [57]    [58]    [59]    [60]    
[41]    [42]    [43]    [44]    [45]    [46]    [47]    [48]    [49]    [50]    
[31]    [32]    [33]    [34]    [35]    [36]    [37]    [38]    [39]    [40]    
[21]    [22]    [23]    [24]    [25]    [26]    [27]    [28]    [29]    [30]    
[11]    [12]    [13]    [14]    [15]    [16]    [17]    [18]    [19]    [20]    
[1]     [2]     [3]     [4]     [5]     [6]     [7]     [8]     [9]     [10]
```

Where each number here would correspond to an item in the list.

E.g.,

```python
[0] Text: '# Report Title'
[1] Plot: https://plot.ly/~jackp/1
[2] Grid: https://plot.ly/~jackp/2
[3] Text: 'Lorem ipsum dolor sit amet, cons...'

[ 0 (Text) ]
[ 1 (Plot) ]    [ 2 (Grid) ]
[ 3 (Text) ]
```