allow to launch tracim with uwsgi

[inkhey]

Documentation + some code to use tracim with uwsgi.
closes #67.

Optimisations needed for readme in #72

[coveralls]

Pull Request Test Coverage Report for Build 88

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 74.594%

---

Totals
Change from base Build 78:	0.0%
Covered Lines:	3817
Relevant Lines:	5117

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 88

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 74.594%

---

Totals
Change from base Build 78:	0.0%
Covered Lines:	3817
Relevant Lines:	5117

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 99

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.3%) to 74.899%

---

Files with Coverage Reduction	New Missed Lines	%
tracim/lib/core/user.py	2	97.14%

Totals
Change from base Build 78:	0.3%
Covered Lines:	3879
Relevant Lines:	5179

---

💛 - Coveralls

[lebouquetin]

@inkhey it will be important to update this documentation when radicale will be migrated.

Good job.