Adding Karaf feature for Olingo

To use Olingo in OSGi, you need to install some additional bundles in addition to those Olingo's bundles. In order to make this process simpler for Apache Karaf users, we can define Karaf features for Olingo. This will allow the users to simply run the install command, as

karaf@root()> feature:install olingo-server
karaf@root()> feature:install olingo-client

and the relevant bundles are automatically deployed, as
karaf@root()> list
START LEVEL 100 , List Threshold: 50
ID | State | Lvl | Version | Name
--------------------------------------------------------------------------
97 | Active | 50 | 1.9.0 | Apache Commons Codec
98 | Active | 50 | 3.3.2 | Apache Commons Lang
99 | Active | 50 | 3.1.4 | Stax2 API
100 | Active | 50 | 0.9.10 | aalto-xml
101 | Active | 50 | 4.1 | antlr4-runtime
102 | Active | 50 | 2.4.2 | Jackson-core
103 | Active | 50 | 2.4.2 | Jackson-annotations
104 | Active | 50 | 2.4.2 | jackson-databind
105 | Active | 50 | 4.0.0.SNAPSHOT | odata-commons-api
106 | Active | 50 | 4.0.0.SNAPSHOT | odata-commons-core
107 | Active | 50 | 4.0.0.SNAPSHOT | odata-server-api
108 | Active | 50 | 4.0.0.SNAPSHOT | odata-server-core
109 | Active | 50 | 2.4.0 | Commons IO
110 | Active | 50 | 4.2.5 | Apache Apache HttpCore OSGi bundle
111 | Active | 50 | 4.2.6 | Apache Apache HttpClient OSGi bundle
112 | Active | 50 | 2.4.2 | Jackson-module-JAXB-annotations
113 | Active | 50 | 2.4.2 | Jackson-dataformat-XML
114 | Active | 50 | 4.0.0.SNAPSHOT | odata-client-api
115 | Active | 50 | 4.0.0.SNAPSHOT | odata-client-core
karaf@root()>