write_csv: Disable scientific notation for integers

[zeehio]

Large integer numbers are not properly handled by write_csv as they are saved in scientific notation losing precision.

This PR is a followup of #679 much more simplified and hopefully closer to what @jimhester has in mind 😃

Thanks for your time reviewing it :-)

[simecek]

I have run into a similar problem with Kaggle competition: https://www.kaggle.com/c/web-traffic-time-series-forecasting/data

The input file train_2.csv contains Wikipedia traffic data, i.e. how many times the given page (in rows) was accessed on a given date (in columns). The read_csv function warned me that 37603th row was not parsed properly. That happened because of "1e+05" that parse_integer fails to parse as demonstrated below:

> parse_integer(c("1e05", "2", "3"))
Warning: 1 parsing failure.
row # A tibble: 1 x 4 col     row   col               expected actual expected   <int> <int>                  <chr>  <chr> actual 1     1    NA no trailing characters    e05
[1] NA  2  3
attr(,"problems")
# A tibble: 1 x 4
    row   col               expected actual
  <int> <int>                  <chr>  <chr>
1     1    NA no trailing characters    e05 
> parse_double(c("1e05", "2", "3"))
[1] 1e+05 2e+00 3e+00

I am not sure how train_2.csv file was created and whether it is a problem of write_csv or not. However something similar is to be expected for any large file of integers just by a pure chance.

Inability to write data with write_csv and reading them back with read_csv (without specification of column types) might be challenging for beginners. I would suggest either accept this pull request or modify parse_integer to accept a scientific notation.

[zeehio]

This PR closes #845 :-)

[jimhester]

Thanks for the PR and for your patience in getting it merged!