last PEP8 fixes (everything but E501 line too long and E123 close bracket indent)
These two commits fix all the rest of the PEP8 errors and warnings except for:
* E123 closing bracket does not match indentation of opening bracket's line
* E501 line too long (x > 79 characters)
Almost all of the fixed issues were these errors:
* E124 closing bracket does not match visual indentation
* E125 continuation line does not distinguish itself from next logical line
* E126 continuation line over-indented for hanging indent
* E127 continuation line over-indented for visual indent
* E128 continuation line under-indented for visual indent
* E226 missing whitespace around arithmetic operator
If you would like to make it run as part of the automated builds, it would just be a matter of adding this line to `jenkins-build`:
```
pep8 --ignore=E123,E501,W fdroid fdroidserver/*.py examples/*.py
```
* E124 closing bracket does not match visual indentation
* E125 continuation line does not distinguish itself from next logical line
* E126 continuation line over-indented for hanging indent
* E127 continuation line over-indented for visual indent
* E128 continuation line under-indented for visual indent
fix pyflakes error and a bunch of PEP8 fixes
lots of little fixes here, the first commit fixes the minor error that `pyflakes` raised, then the rest are all PEP8 fixes, as reported by the `pep8` command line tool.
pyflakes gave this error based on the `paramiko = None` statement. I used
a different way to test whether paramiko was successfully imported that is
directly based on the relevant Exceptions.
Aside from the VM setup (which is now self-contained) the build process
only cares that it's handed a clean VM that it can access via ssh, given
a host/port/user/pubkey combination. There's no dependency outside the
getvm/releasevm functions on what kind of vm it is, what user the build
runs as, etc.
fdroidclient now uses SHA256 fingerprints internally, and they are shown in
the repo details view. This changes the digest algorithm to SHA256 and
changes the format to match what is shown in the repo details view.
