test_web.py: fix test_GET_DIRECTORY_html_filenode_encoding for Twisted==12.3.0. fixes #1922

twisted.web.html.escape was used to produce html-encoded string (to then look
it up in "value" attribute), but behavior of that function has changed between
Twisted 12.2.0 (simple custom implementation) and 12.3.0 (imported from stdlib
cgi module).
Only quote newline characters where necessary. fixes #1484

Signed-off-by: David-Sarah Hopwood <david-sarah@jacaranda.org>
tahoe_ls.py: JSON responses don't need quotemarks or quoted newlines.

Signed-off-by: David-Sarah Hopwood <david-sarah@jacaranda.org>
Add test for anti-Ubuntu-crash-reporter exception-catching code. fixes #1746

Signed-off-by: David-Sarah Hopwood <david-sarah@jacaranda.org>
Ensure that bin/tahoe and setup.py fail quickly on Python 3.3+. fixes #1775

Signed-off-by: David-Sarah Hopwood <david-sarah@jacaranda.org>
Make doubly sure that we fail quickly on future Python 3.x versions. refs #1775

Signed-off-by: David-Sarah Hopwood <david-sarah@jacaranda.org>
Require at least Python 2.6. fixes #1658

Signed-off-by: David-Sarah Hopwood <david-sarah@jacaranda.org>
bump 'mock' dependency to >=0.8.0, to get the .call object

The 0.6.0 version that was previously allowed did not provide .call, so
test_cli.py failed during import.