Update cleaning of dataset

[erictleung]

• Change commute times >300 minutes to NA
• Change minimum mortgage to $1000 and maximum mortgage to $1000000
• Move data dictionary into clean-data/ directory
• Change minimum student debt to $1000 and maximum debt to $500000
• Add changelog to clean data README
• Remove missing data encoding information in README
• Add example exploration in clean data README
• Add figure of distribution of ages in dataset
• Change naming of some columns that were originally extracted from "Other"
  columns in the dataset to reflect columns were derived, rather than
  originally being there
• Clean data for children to make sure number of children and yes/no answer to
  having children is consistent
• Fix spelling mistake in IsReceiveDisabilitiesBenefits (original:
  IsReceiveDiabilitiesBenefits)
• Use ungroup() command in time_diff_check because of dplyr version
  changes
• Separate polishing steps for podcasts, resources, and so on to make it easier
  to see what is being polished
• Update survey data dictionary description with details on the two datasets
  and parts of the survey
• Update survey data
• Update version numbers for R packages

cc/ @evaristoc @SamAI-Software @QuincyLarson

Close #33

[QuincyLarson]

@erictleung I am unfamiliar with R so I don't feel qualified to QA this, but all of these changes you described sound sane :)

[SamAI-Software]

The issues might be because some people already did their analyses, so changing variable names will break their code. Mine, too.
I understand the reasons why Eric changed names and fixed typos, but it might be too late for that.

[erictleung]

Right, I understand that I've changed those variables names and it will break some people's code. @evaristoc and I discussed the reason for renaming the variable names with Other in them. And I agree, it might be too late at this point.

I guess it is not too urgent that those variable names be changed. I can revert them back and just make a note of it in the README file.

The most important part of the change is the normalization part to address issue #33.

[SamAI-Software]

The most important part of the change is the normalization part to address issue #33.

This part seems to be fine.

If you revert the old variable names and add a note into README, then we should be good to go.

[erictleung]

@SamAI-Software awesome, I'll try to get to it later tonight.

[erictleung]

@SamAI-Software updated my PR!

I reverted the major change of adding Other into the variables names. I did, however, keep the variable change for IsReceiveDisabilitiesBenefits as the original IsReceiveDiabilitiesBenefits has a typo.

Feel free to pull down my PR and QA check the dataset. Let me know if there's anything else of concern 😃

[SamAI-Software]

LGTM