Allow per-channel settings

This commit makes it possible to get/set a setting for a specific PEAR
channel. This is done by adding a new option to the get/set commands
(-c/--channel) which can be used to pass the name of the PEAR channel
to operate on.
See pyrus/Pyrus#7
Check MIME type of signature files

When attempting to check a package's release against its signature, a
check should first be made against the signature's MIME type, to avoid
throwing exceptions (releasing maintainer's certificate is not a
certificate) when something else was returned (like an HTML page).

Also, don't throw an exception immediately when the downloaded package
could not be parsed. Again, the server may have returned something
completely different. We wait until all attempts (using different file
extensions) to download a valid package have failed before bailing out.

See pyrus/Pyrus#32 for more information.
PEAR2 packages are now hosted on github.
Merge branch 'master' of github.com:saltybeagle/Pyrus
Change channel from pear2.php.net to pyrus.net
Data path has changed now that the channel is pyrus.net
Change channel name from pear2.php.net to pyrus.net. Closes #53

All packages related to the installer and channel infrastructure will be
released on the pyrus.net PEAR channel, and use the Pyrus package name
and vendor prefix.
Remove realpath call for performance and to fix paths inside the phar,
see https://bugs.php.net/bug.php?id=52769
Add pyrus.net (pyrus) as a default channel. Closes #68
Update expected output when channels have no installed packages. #58
Change autoloader to reflect package name change from PEAR2_Pyrus to Pyrus
Fix extrafiles string regression.

\Pyrus\Package\Creator::addExtraFiles suddenly stopped accepting strings as
valid values for $extrafiles after pyrus/Pyrus@efc3a883cbcf5512d03602e9aa8dcdc42bbbe620.
Fixes pyrus/Pyrus#71.
Add test for extrafiles regression.
Merge pull request #73 from fpoirotte/71_extrafiles_as_strings

Regression: $extrafiles does not accept strings anymore
Use space instead of \n for the schemaLocation list

The \XMLWriter class will convert attributes with newlines into these to
&#10; and &#13;. To work-around this issue, Pyrus\XMLWriter removes
newline characters which affects the channel.xml root attributes.
Merge pull request #74 from saltybeagle/master

Use space instead of \n for the channel schemaLocation list
Allow per-channel settings

This commit makes it possible to get/set a setting for a specific PEAR
channel. This is done by adding a new option to the get/set commands
(-c/--channel) which can be used to pass the name of the PEAR channel
to operate on.
See pyrus/Pyrus#7
Check MIME type of signature files

When attempting to check a package's release against its signature, a
check should first be made against the signature's MIME type, to avoid
throwing exceptions (releasing maintainer's certificate is not a
certificate) when something else was returned (like an HTML page).

Also, don't throw an exception immediately when the downloaded package
could not be parsed. Again, the server may have returned something
completely different. We wait until all attempts (using different file
extensions) to download a valid package have failed before bailing out.

See pyrus/Pyrus#32 for more information.
Misc improvements over 27fa3e7 and tests.
Merge branch 'per_channel_settings' of github.com:fpoirotte/Pyrus into per_channel_settings

Conflicts:
	src/Pyrus/ScriptFrontend/Commands.php