Set up documentation + lint (#121)

- remove some automatically generated stuff not should even be in
repository
- set up lint + Documents.jl in same way it is defined in freshly started projects
- add lint + doctest to after_success so that build pass, these needs to be fixed later
- build is failing on nightly (0.7) but it's ok for release (0.5.2)
- Documenter.jl supports doctests, so this closes least #23
- build system is now on Travis-CI completely, so this closes also #68

docs/src/index.md

@@ -0,0 +1,24 @@
+# JuliaFEM.jl documentation
+
+```@contents
+```
+
+```@meta
+DocTestSetup = quote
+    using JuliaFEM
+end
+```
+
+## Constants
+
+Add here.
+
+## Functions
+
+Add here.
+
+## Index
+
+```@index
+```
+