Identity v3 Projects List (#163)

* Identity v3 Projects List

* Rename ToListQuery to ToProjectListQuery
diff --git a/openstack/identity/v3/projects/requests.go b/openstack/identity/v3/projects/requests.go
new file mode 100644
index 0000000..213db9c
--- /dev/null
+++ b/openstack/identity/v3/projects/requests.go
@@ -0,0 +1,52 @@
+package projects
+
+import (
+	"github.com/gophercloud/gophercloud"
+	"github.com/gophercloud/gophercloud/pagination"
+)
+
+// ListOptsBuilder allows extensions to add additional parameters to
+// the List request
+type ListOptsBuilder interface {
+	ToProjectListQuery() (string, error)
+}
+
+// ListOpts allows you to query the List method.
+type ListOpts struct {
+	// DomainID filters the response by a domain ID.
+	DomainID string `q:"domain_id"`
+
+	// Enabled filters the response by enabled projects.
+	Enabled *bool `q:"enabled"`
+
+	// IsDomain filters the response by projects that are domains.
+	// Setting this to true is effectively listing domains.
+	IsDomain *bool `q:"is_domain"`
+
+	// Name filters the response by project name.
+	Name string `q:"name"`
+
+	// ParentID filters the response by projects of a given parent project.
+	ParentID string `q:"parent_id"`
+}
+
+// ToProjectListQuery formats a ListOpts into a query string.
+func (opts ListOpts) ToProjectListQuery() (string, error) {
+	q, err := gophercloud.BuildQueryString(opts)
+	return q.String(), err
+}
+
+// List enumerats the Projects to which the current token has access.
+func List(client *gophercloud.ServiceClient, opts ListOptsBuilder) pagination.Pager {
+	url := listURL(client)
+	if opts != nil {
+		query, err := opts.ToProjectListQuery()
+		if err != nil {
+			return pagination.Pager{Err: err}
+		}
+		url += query
+	}
+	return pagination.NewPager(client, url, func(r pagination.PageResult) pagination.Page {
+		return ProjectPage{pagination.LinkedPageBase{PageResult: r}}
+	})
+}