Updating TODO to reflect Py3 support in Thrift.

[dhermes]

@wbolster FWIW I may also be willing / able to assist on #40. I was very worried that Thrift would require updating, but saw your comment and then confirmed thrift at least installs for Python 3.

Interested because we are considering building a layer around happybase for Google's newly released Cloud BigTable.

[dhermes]

Looks like https://issues.apache.org/jira/browse/THRIFT-1857 is not as complete as it seemed before I finished reading all of #40.

[landscape-bot]

Repository health increased by 0.38% when pulling 2a71540 on dhermes:update-todo-re-py3 into 6205177 on wbolster:master.

• 1 new problem was found (including 0 errors and 1 code smell).
• 19 problems were fixed (including 2 errors and 5 code smells).

[wbolster]

Thanks merged. I've not really dived into #40; it seems Thrift had (at some point) problems with Python 3. Additionally, some code in Happybase would need some adaptation (mostly compat code for bytes/text boundaries).

[dhermes]

@wbolster As a start, #78 should be merged, or at the least the part that uses exec(open(...)) instead of execfile.

It'd be even better if exec could be ditched for something like from {NAME} import *.