add ceph backing store plugin

.travis.yml

@@ -1,32 +1,45 @@
 sudo: required
 dist: trusty
 env:
-    - TARGET=iqn.2016-09.com.gotgt.gostor:example_tgt_0
+    global:
+        - TARGET=iqn.2016-09.com.gotgt.gostor:example_tgt_0
+    matrix:
+        - TGT_CFG='{"storages":[{"deviceID":1000,"path":"file:/var/tmp/disk.img","online":true}],"iscsiportals":[{"id":0,"portal":"127.0.0.1:3260"}],"iscsitargets":{"iqn.2016-09.com.gotgt.gostor:example_tgt_0":{"tpgts":{"1":[0]},"luns":{"0":1000}}}}'
+        - TGT_CFG='{"storages":[{"deviceID":1000,"path":"ceph-rbd:iscsi_pool/lun0","online":true}],"iscsiportals":[{"id":0,"portal":"127.0.0.1:3260"}],"iscsitargets":{"iqn.2016-09.com.gotgt.gostor:example_tgt_0":{"tpgts":{"1":[0]},"luns":{"0":1000}}}}'
 
 language: go
+
 go:
     - 1.6
+    - 1.7
+    - 1.8
 
 install:
    - true
 
 before_script:
-    - go get github.com/kr/godep
+    - echo ${TGT_CFG}
+    - echo ${TARGET}
     - sudo apt-get update
+    - ci/ceph_install.sh
+    - bash ci/ceph_micro-osd.sh /tmp/micro-ceph
+    - export CEPH_CONF=/tmp/micro-ceph/ceph.conf
+    - ceph status
+    - go get github.com/kr/godep
     - sudo apt-get install -y libcunit1 libcunit1-doc libcunit1-dev
     - sudo apt-get install -y open-iscsi
 
 script:
    - cd ${TRAVIS_BUILD_DIR}
    - ./autogen.sh
-   - ./configure 
+   - ./configure
    - make
    - hack/verify-gofmt.sh
    - export GOPATH=`pwd`/Godeps/_workspace/:$GOPATH
    - go test -v ./pkg/...
    - dd if=/dev/zero of=/var/tmp/disk.img bs=1024 count=10240
    - mkdir ${HOME}/.gotgt
-   - echo '{"storages":[{"deviceID":1000,"path":"file:/var/tmp/disk.img","online":true}],"iscsiportals":[{"id":0,"portal":"127.0.0.1:3260"}],"iscsitargets":{"iqn.2016-09.com.gotgt.gostor:example_tgt_0":{"tpgts":{"1":[0]},"luns":{"0":1000}}}}' > ${HOME}/.gotgt/config.json
+   - echo ${TGT_CFG} > ${HOME}/.gotgt/config.json
    - ./gotgt daemon --log debug 1>/dev/null 2>&1 &
    # libiscsi test
    - mkdir ${HOME}/libiscsi