Fix #1770: Provide support for setting BuildConfig memory/CPU requests and limits

[rohanKanojia]

Fix #1770

This PR provides the support of configuring BuildConfig's spec using xml config or as a resource fragment. You can have xml config like this:

            <plugin>
                <groupId>io.fabric8</groupId>
                <artifactId>fabric8-maven-plugin</artifactId>
                <version>4.4-SNAPSHOT</version>
                <configuration>
                  <resources>
                    <openshiftBuildConfig>
                      <limits>
                        <cpu>100m</cpu>
                        <memory>256Mi</memory>
                      </limits>
                    </openshiftBuildConfig>
                  </resources>
                </configuration>
            </plugin>

[devang-gaur]

not a serious change request but can you group the class properties together and the functions together?

[devang-gaur]

can you eliminate the hard coding here and all the places where SourceType property is used?

[manusa]

LGTM