Added E741 to flake8 config
Makes this easier to run locally.

Do we want to ignore bare exception (E722) too? Or is the hope that we'll fix all those eventually?
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19496?src=pr&el=h1) Report
> Merging [#19496](https://codecov.io/gh/pandas-dev/pandas/pull/19496?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/78ba063f438924378f887d77fcc692186e6381a6?src=pr&el=desc) will **increase** coverage by `0.02%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19496/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/19496?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #19496      +/-   ##
==========================================
+ Coverage   91.67%    91.7%   +0.02%     
==========================================
  Files         148      148              
  Lines       48553    48553              
==========================================
+ Hits        44513    44525      +12     
+ Misses       4040     4028      -12
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.06% <ø> (+0.02%)` | :arrow_up: |
| #single | `41.72% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/19496?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/19496/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `66.95% <0%> (+1.73%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19496?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19496?src=pr&el=footer). Last update [78ba063...9abcb98](https://codecov.io/gh/pandas-dev/pandas/pull/19496?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 no the excepts should be fixed (there is an issue)
the 1 letter variables are prob ok  thanks! Hey - out of interest how come we ignore this error (E741) I don't see any instances of it in the codebase and thinking we could now enforce it? Not sure. I may have copied it from another config (this came from updates
to flake8's rules).

On Tue, Sep 18, 2018 at 7:43 PM alimcmaster1 <notifications@github.com>
wrote:

> Hey - out of interest how come we ignore this error (E741) I don't see any
> instances of it in the codebase and thinking we could now enforce it?
>
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