Using MODE_CBC instead of MODE_ECB in README example

ECB mode has known disadvantages and while the use of it could be
intended, I think it would be a good idea to have a 'stronger' mode in
the example.

Thus, I adopted the example in the README to make use of MODE_CBC
instead of MODE_ECB.
Run test_negative_number_roundtrip_mpzToLongObj_longObjToMPZ only if _fastmath
is available.
Store result of rabinMillerTest in an int.

rabinMillerTest returns an int but getStrongPrime stores the result in an
unsigned long int which makes the tests in line 1545 and 1621 useless.
Add tests for error propagation in _fastmath

Affects isPrime and getStrongPrime.

See https://github.com/dlitz/pycrypto/pull/23 ("Store result of
rabinMillerTest in an int.") for the bug report.
Merge remote-tracking branch 'sebastinas/clang' into error-propagation-fixes

Pull request: https://github.com/dlitz/pycrypto/pull/23
_fastmath: Propagate errors raised in rabinMillerTest
Merge branch 'error-propagation-fixes'
Fix typo in comment
_fastmath: Use default false_positive_prob is one is not specified

This should never happen, but the behaviour is saner if it does.
_fastmath: Replace 'long int' with 'long' to avoid confusion

"long int" is equivalent to "long" in C, and it's harder to misread it as
"int" this way.
setup.py: Add more compiler warnings and fix unsigned-signed comparisons
Merge remote-tracking branch 'aried3r/master'

Pull request: https://github.com/dlitz/pycrypto/pull/19
Check in some scripts I use for building and testing against multiple versions of Python
Add build to TestCommand's sub_commands

... and run the sub_commands in TestCommand.run. So if python setup.py test is
executed before ever running the build target, the extension modules are built.

Bug: https://bugs.launchpad.net/pycrypto/+bug/1055256
Bug: https://bugs.launchpad.net/pycrypto/+bug/976171
Use os.chmod instead of os.system("chmod ...")