loadbalance: fix help message for -s option
loadbalance: fix info message formatting bug
awsutils: raise exc in wait_for_propagation after max_retries

EasyEC2.wait_for_proagation now raises an exception if the objects are
not able to be refetched after max_retries.

Increased max_retries to 60 in order to give enough time (5mins by
default which should be overkill) for the API to return the desired
objects (ie spot or instance requests) before raising the exception. For
some reason the filters API seems to take longer than the query list
method to return spot requests in some regions (e.g. us-west-2). For
example, from limited testing at the time of this commit it seems the
following command in us-west-2 region:

$ aws ec2 describe-spot-instance-requests --spot-instance-request-ids \
sir-blahblah2

takes longer to return the newly created spot request than the equivalent
'filter' version of the command:

$ aws ec2 describe-spot-instance-requests --filters \
Name=spot-instance-request-id,Values=sir-blahbla2
use proc ratios to tune
fix style
stupid string formatting
wake up
hadoop: document all advanced settings
spothistory: use history data for plot's date range heading

This more accurately shows the date range that was returned by Amazon
for the start and end times requested by the user. It also ensures the
plot shows the date range regardless of whether the user specified an
exact range, an approximate range (e.g. --days-ago) or no range at all.
utils: use UTC timezone for all time stamps

Switched to using iso8601 in iso_to_datetime_tuple which handles all the
various iso8601 formats and sets any timezone info provided in a given
format accordingly in the resulting datetime object. After parsing the
iso date and zone properly it's then converted to UTC time and returned.

Updated datetime_tuple_to_iso to convert the tuple to UTC first before
formatting. Updated the formatting to include the microseconds and UTC
timezone indicator (Z).
spothistory: improve date calcs for -s, -e, and -d options

Updated the code to pass start=None and end=None if no specific ranges
were specified (ie -s, -e, and -d options). When -d is specified only
the start time is calculated using local time (converted to UTC) -
end=None is still used unless the user explicitly sets -e option in
which case the start time is calculated based on the end time minus the
number of days specified by -d. This avoids discrepancies between the
AWS console starcluster in the case that the user's local time is off.

Added a check to error out if both -d and -s options are specified.

Added a note to the spothistory web template that all timestamps
displayed in the plot are UTC.
spothistory: clean-up unused datetime import
utils: pep8 cleanup
use UTC tzinfo for timestamps in loadbalancer tests
Waits for pg and sg deletion propagation
using isinstance rather than type compare
Removed message prints, sleep 5 seconds between checks
removenode: prompt for confirmation and add -c option

The -c option works the same as the terminate, removevolume, etc.
commands - it skips the prompt for confirmation.
docs: add git hooks setup to contribute guide
docs: document how to run tests in contribute guide