Add yaml and ini parsers

[bogdandm]

(Fixes #37)

Add yaml and ini file parsers.

class YamlFile(BaseModel):
    swagger: float
    schemes: List[Literal["https"]]
    host: Literal["api.spotify.com"]
    base_path: Literal["/v1"] = Field(..., alias="basePath")
    info: 'Info'
    external_docs: 'ExternalDoc_XLogo' = Field(..., alias="externalDocs")
    consumes: List[Literal["application/json"]]
    produces: List[Literal["application/json"]]
    security_definitions: 'SecurityDefinition' = Field(..., alias="securityDefinitions")
    paths: 'Path'
    definitions: 'Definition'

...

class IniFile(BaseModel):
    owner: 'Owner'
    database: 'Database'


class Owner(BaseModel):
    name: Literal["John Doe"]
    organization: Literal["Acme Widgets Inc."]


class Database(BaseModel):
    server: Literal["192.0.2.62"]
    port: int
    file: Literal["payroll.dat"]

[coveralls]

Coverage decreased (-0.5%) to 97.955% when pulling 9895ea7 on yaml-ini-parsers into d00e80d on master.