Simplify and test Percona::WebAPI::Client.pm according to new web API specs.

lib/Percona/WebAPI/Resource/Agent.pm

@@ -38,7 +38,13 @@ has 'versions' => (
    is       => 'ro',
    isa      => 'Maybe[HashRef]',
    required => 0,
-   default  => undef,
+);
+
+has 'links' => (
+   is       => 'rw',
+   isa      => 'Maybe[HashRef]',
+   required => 0,
+   default  => sub { return {} },
 );
 
 no Lmo;

lib/Percona/WebAPI/Resource/Config.pm

@@ -22,12 +22,31 @@ package Percona::WebAPI::Resource::Config;
 
 use Lmo;
 
+has 'id' => (
+   is       => 'r0',
+   isa      => 'Int',
+   required => 1,
+);
+
+has 'name' => (
+   is       => 'ro',
+   isa      => 'Str',
+   required => 1,
+);
+
 has 'options' => (
    is       => 'ro',
    isa      => 'HashRef',
    required => 1,
 );
 
+has 'links' => (
+   is       => 'rw',
+   isa      => 'Maybe[HashRef]',
+   required => 0,
+   default  => sub { return {} },
+);
+
 no Lmo;
 1;
 }

lib/Percona/WebAPI/Resource/Run.pm

@@ -44,7 +44,6 @@ has 'query' => (
    is       => 'ro',
    isa      => 'Maybe[Str]',
    required => 0,
-   default  => undef,
 );
 
 has 'output' => (

lib/Percona/WebAPI/Resource/Service.pm

@@ -46,6 +46,13 @@ has 'spool_schedule' => (
    required => 0,
 );
 
+has 'links' => (
+   is       => 'rw',
+   isa      => 'Maybe[HashRef]',
+   required => 0,
+   default  => sub { return {} },
+);
+
 sub BUILDARGS {
    my ($class, %args) = @_;
    if ( ref $args{runs} eq 'ARRAY' ) {