Update contributing.md with new integration process ...

Contributions will now be merged into an ARM Trusted Firmware
integration branch on GitHub instead of via an ARM internal
branch.

Remove change log instructions from contribution.md ...

Remove the instructions to update the change log from
contribution.md. The change log no longer contains a
"Detailed changes since last release" section.

Also, update the documentation links following recent
documentation changes.

Change-Id: Id9df43d666f7f9a60dcc6f663a8a85cdd2ff7cc4

Update contributing.md to new CLA location ...

This commit updates contributing.md to point to the ARM website
for downloading copies of the Contribution License Agreement (CLA).
It is no longer necessary to email ARM for these.

Change-Id: Iaf58680631a626f26827577709ac5471e3b84566

Allow style checking of tree and local changes ...

New phony Makefile targets have been added:

 * checkcodebase
 * checkpatch

The checkcodebase target will run a Linux style compliance check over the
entire codebase, and honours the V=1 Makefile verbose setting and so will
show more information when this is enabled.

If the local directory is a git checkout then the output of git ls-files is
used to decide which files to test for compliance.  If the local directory
is not under git control then a 'best attempt' is made, but in this case it
should be noted that it is possible for additional non-codebase files to be
tested, so care should be taken when parsing the output.

The checkpatch target will compare local changes against the git origin/master
to allow issues with the last set of changes to be identified.  To override
the change comparision location, set the BASE_COMMIT variable to your
desired git branch.

Both targets rely on the Linux source tree script checkpatch.pl to do the
syntax checking, and expects that the CHECKPATCH environment variable points
to the location of this file.

Notes on the usage of these targets have been added to the contributing.md
and docs/user-guide.md text files.

Change-Id: I6d73c97af578e24a34226d972afadab9d30f1d8d

Update year in copyright text to 2014 ...

Change-Id: Ic7fb61aabae1d515b9e6baf3dd003807ff42da60

Refer to separate issue tracking repository ...

Update documentation to refer to separate issue tracking
repository, https://github.com/ARM-software/tf-issues/issues.

Change-Id: Ib1cef65b0da420bec58290d8743eb069b1226c96

Enable third party contributions ...

- Add instructions for contributing to ARM Trusted Firmware.

- Update copyright text in all files to acknowledge contributors.

Change-Id: I9311aac81b00c6c167d2f8c889aea403b84450e5