ASTERIXDB-1160: Break deadlock between LogManager and LogFlusher

This change introduces a new thread in LogManager to log FLUSH logs.
This will prevent LogFlusher thread from waiting on itself until FLUSH logs are flushed to disk.

Change-Id: I0b414f5ab92e1c68c8aafbaab859c644ba399dcb
Reviewed-on: https://asterix-gerrit.ics.uci.edu/475
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: abdullah alamoudi <bamousaa@gmail.com>
diff --git a/asterix-lang-common/pom.xml b/asterix-lang-common/pom.xml
index 974212b..1e22da0 100644
--- a/asterix-lang-common/pom.xml
+++ b/asterix-lang-common/pom.xml
@@ -43,8 +43,8 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
-                    <source>1.7</source>
-                    <target>1.7</target>
+                    <source>1.8</source>
+                    <target>1.8</target>
                     <fork>true</fork>
                 </configuration>
             </plugin>