.travis.yml: activate build on Oracle JDK 8.
Use BigDecimal for series' price (instead of Double).

Fix build under JDK8.

See details at: https://travis-ci.org/php-coder/mystamps/jobs/39317412
/series/add: fix ordering of countries' names.

Correction for 7434210c5fd10af188a0b01b98c172c219283c57 commit.
/series/add: fix ordering of categories' names.

Correction for 0cf288e5d0882e5e4c3a2437905f5d352b72380ac commit.
Change style of headers: removed caps.

[ci skip]
pom.xml(maven-compiler-plugin): updated to 3.2

@see http://mail-archives.apache.org/mod_mbox/maven-users/201410.mbox/%3C543C1BBA.2050801@commonjava.org%3E

No functional changes.
pom.xml(maven-war-plugin): updated to 2.5

@see http://mail-archives.apache.org/mod_mbox/maven-dev/201307.mbox/%3CCAPoyBqQK_xpD73WD4nRfccvzUVoXuZW5DmNxAKomOjyBnLvG2w@mail.gmail.com%3E
@see http://mail-archives.apache.org/mod_mbox/maven-users/201410.mbox/%3C20141012133211.A731D174D6@minotaur.apache.org%3E

No functional changes.
enable checking