[iOS] renaming to Cordova - and upgrades

[Shazron <sh...@gmail.com>]

Hi,
I've completed the rename changes and they have been committed in.

Several things of note:
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1. A Cordova install exists side by side with a PhoneGap <= 1.4.x
install, in their own separate folders. I decided not to do any fancy
symlinking, etc to have backwards compatibility since this will just
hide the problem for devs, and is not transparent - and from
experience, will cause headaches later.
2. Because of the previous point - it is possible to have in Xcode the
option to create a "PhoneGap-based application" and a "Cordova-based
application" - users that need to uninstall PhoneGap will have to get
and run the "Uninstall PhoneGap" app from a PhoneGap .dmg distribution
3. Existing PhoneGap <= 1.4.x projects WILL break, and devs will need
to consult the Project Upgrade Guide and have to upgrade manually.
4. Existing PhoneGap <= 1.4.x plugins WILL break, and devs will need
to consult the Plugin Upgrade Guide and have to upgrade manually. I
plan to include in the .dmg distribution several (deprecated) classes
that subclass from the new classes to ease the upgrade, but decided
not to include them in the core.
5. To upgrade a project that is < 1.4.x, you will have to do a two
step process - upgrade from <= 1.3 to 1.4.x, then 1.4.x to 1.5
6. As a rule of thumb, any classes prefixed with PG have been changed
to have the prefix CDV. Any classes that did not have CDV as a prefix,
have them added now. Any filenames that did not have the prefix CDV,
have CDV added as a prefix now. This 2 or more character prefix is how
Obj-C "namespaces" things, and will help us avoid conflicts with other
libraries during linking in the future.

TODO still:
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1. cordova-js unified JavaScript
2. Upgrade Guide for upgrading a Project
3. Upgrade Guide for upgrading a Plugin