Update 'db/install.xml'

Increased field lengths of:
* gradeimporter.name: from 50 to 256 (<FIELD NAME="name" TYPE="char" LENGTH="256" ...)
*  gradeimporter_submission.name: from 20 to 256 (<FIELD NAME="name" TYPE="char" LENGTH="256"...)

db/install.xml

@@ -9,7 +9,7 @@
         <FIELD NAME="id" TYPE="int" LENGTH="10" NOTNULL="true" UNSIGNED="true" SEQUENCE="true" ENUM="false" COMMENT="primary key" NEXT="course"/>
         <FIELD NAME="course" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false" COMMENT="The id of the course this instance is placed on" 
                   PREVIOUS="id" NEXT="name"/>
-        <FIELD NAME="name" TYPE="char" LENGTH="50" NOTNULL="true" SEQUENCE="false" ENUM="false" COMMENT="Instance name" PREVIOUS="course" NEXT="intro"/>
+        <FIELD NAME="name" TYPE="char" LENGTH="256" NOTNULL="true" SEQUENCE="false" ENUM="false" COMMENT="Instance name" PREVIOUS="course" NEXT="intro"/>
         <FIELD NAME="intro" TYPE="text" NOTNULL="false" SEQUENCE="false" COMMENT="Description of the grades that are going to be available on the module" 
               PREVIOUS="NAME" NEXT="timecreated"/>
         <FIELD NAME="timecreated" TYPE="int" LENGTH="10" NOTNULL="true" DEFAULT="0" SEQUENCE="false" COMMENT="Time stamp from when the instance was first created" 
@@ -38,7 +38,7 @@
                 PREVIOUS="timecreated" NEXT="usermodified"/>
         <FIELD NAME="usermodified" TYPE="int" LENGTH="10" NOTNULL="true" DEFAULT="0" SEQUENCE="false"
                 PREVIOUS="timemodified" NEXT="name"/>
-        <FIELD NAME="name" TYPE="char" LENGTH="20" NOTNULL="true" SEQUENCE="false" COMMENT="submission name"
+        <FIELD NAME="name" TYPE="char" LENGTH="256" NOTNULL="true" SEQUENCE="false" COMMENT="submission name"
                 PREVIOUS="usermodified" NEXT="info"/>
         <FIELD NAME="description" TYPE="text" NOTNULL="false" SEQUENCE="false" COMMENT="Description of the submission type ex: exam 1 given on day YYYY/MM/DD"
               PREVIOUS="name" NEXT="descriptionformat"/>