Add contributors to composer.json
Use verbose output in behat tests

Easier to debug
Configure options are not stored in pickle.json anymore : m4/w32 will be parsed when installing ext.
Clean configure options handling and display them in the info command
Add some tests on options parsing
Distinguish package root directory and source directory

When downloading from PECL, packages have a root directory containing the package.xml file and a subdirectory containing sources
Add a --defaults option to the install command to avoid prompting the user for configure options values
Clean
Remove -v flag in behat context
Merge pull request #52 from jubianchi/master

Some improvements