Do not delete/recreate transients on page load (debug on)

- Introduce new function to return bool determining if transients
should be ignored
- If that bool is true, always get new data from GitHub API
- set(_site)_transient will update expiration time if transient already
exists, so no need to delete them first (save your options table
indexes!)
Store GitHub data in class instance for future calls

- Store the fetched data in a private class property so it will be
requested from API or transient once per class instance
- Have get_github_data method return this private property if it is not
empty (and thus is set by previous calls)
Merged upstream branch and resolved conflicts
Chane plugin file requested from the readme to the main plugin file. Switch explode over to regex like what is used in get_file_data to retrieve version number.
Merge pull request #21 from coenjacobs/easy-on-transients

Better ways to handle GitHub API calls and temporary store data, props @coenjacobs
Added backwards compatability re discussion on #25
Merge pull request #25 from ninnypants/get_version_from_plugin_file

Get version from plugin header instead of readme with backwards compatibility for the old format (for now).
Fixes #25, props @ninnypants
tidy up code to use WP code standards

* respect WordPress code standards (used PHP tidy to automate this, will do a manual pass next)
* remove trailing whitespace)

ref #27
Readme: start a log of what's being added in 1.6
Readme: add a note about #21
rename the updater class to respect WP standards

rename the class to WP_GitHub_Updater to respect WP naming standards
ref #27, props David Mosterd who emailed me about this
simplify if/return in updater class

ref #27
bump version number to 1.5 (current ver)
require minimum configuration when instantiating the updater

* require a minimum set of configuration when instantiating the updater
* issue a warning and bail if minimum configuration isn't met
* remove bad default configuration
* add a VERSION constant
* bump to 1.6 now that we're deep into it

ref #27
negated the empty() check on line 117
Merge pull request #34 from davidmosterd/fix1

! empty() should be empty(), props davidmosterd
_doing_it_wrong does not show the $message variable
Merge pull request #37 from davidmosterd/fix3

print the `$message` variable in the `_doing_it_wrong()` function, which was an accidental omission.

props @davidmosterd
Updated readme about private repos and changed class name in code sample. Fixes #41
Merge pull request #42 from sudar/readme

Update readme about private repos and change class name in code sample.
props @sudar