Don't incorrectly default charset on FileResponse

By passing the content_type into the constructor to Response, we can allow it to decide intelligently whether the default charset should apply.  Otherwise we'd have to replicate that logic somehow, or live with weird charset annotations on images, pdfs, and zips.
Add tests for the content_type fix.
Expand tests - make sure pdf, jpeg types also are not annotated with a charset.
vb
no longer in progress
Correct missing word.
Merge pull request #1290 from omidraha/patch-1

That looks great, thanks!
revert 1.5-branch version for rtd
More explicit example of set_property

cleanup callback has a "request" parameter (and not "_")
cleanup callback know (since 1.5) if an exception occurred or not (to commit or rollback)
Merge pull request #1302 from flibustenet/patch-1

More explicit example of set_property
Typo fix "not"-->"no"
Corrected the comment's language
Merge pull request #1305 from stevepiercy/1.5-branch

cherry pick #1304 into 1.5-branch
_add_subscriber should resolve dotted names
Add information to CHANGES
Merge pull request #1307 from bertjwregeer/fix.add_predicates_maybe_dotted-1.5

Fix: add predicates maybe dotted 1.5
Correct question to adapt to the the text.

Correct question to adapt to the the text.
- Correct 80-column lines specification to 79 to be compliant with PEP8 and consistent with doc to which this line refers.
Merge pull request #1310 from stevepiercy/1.5-branch

- Correct 80-column lines specification to 79 to be compliant with PEP8 ...
Correct grammar.

Correct grammar.