xml add parents and fix configurations

See merge request !18

Configuration

See merge request !17

Exercise

See merge request !16

Mail module

See merge request !12

Mail module test

See merge request !15

Exercise tests

See merge request !11

Language school user

See merge request !13

# Conflicts:
#   application/model/src/main/java/org/fuseri/model/dto/certificate/CertificateDto.java
#   application/model/src/main/java/org/fuseri/model/dto/course/CourseDto.java
#   application/model/src/main/java/org/fuseri/model/dto/course/LanguageTypeDto.java
#   application/model/src/main/java/org/fuseri/model/dto/lecture/LectureCreateDto.java
#   application/module-certificate/src/main/java/org/fuseri/modulecertificate/service/CertificateController.java
#   application/module-language-school/src/main/java/org/fuseri/modulelanguageschool/course/Course.java
#   application/module-language-school/src/main/java/org/fuseri/modulelanguageschool/course/CourseController.java
#   application/module-language-school/src/main/java/org/fuseri/modulelanguageschool/course/ProficiencyLevel.java
#   application/module-language-school/src/main/java/org/fuseri/modulelanguageschool/lecture/Lecture.java
#   application/module-language-school/src/main/java/org/fuseri/modulelanguageschool/lecture/LectureController.java
#   application/module-language-school/src/test/java/org/fuseri/modulelanguageschool/course/CourseTest.java
#   application/module-language-school/src/test/java/org/fuseri/modulelanguageschool/lecture/LectureTest.java

Language school user tests

See merge request !14

Creating certificate tests

See merge request !8

Lecture tests

See merge request !10

Language school course tests

See merge request !9